Robert J Collier
- Professor, Animal and Comparative Biomedical Sciences
Dr. Collier received his B.S. and M.S. degrees in Zoology from Eastern Illinois University in 1969 and 1973 and his Ph.D. in Dairy Science from the University of Illinois in 1976. After Post-Doctoral studies at Michigan State University, Dr. Collier joined the Dairy Science Department at the University of Florida as an Assistant Professor. He was promoted to Associate Professor in 1981. In July, 1985, Dr. Collier joined the Monsanto Company first as a Science Fellow then Dairy Research Director and Senior Fellow. He oversaw worldwide regulatory studies on bovine somatotropin for the Dairy Industry. From 1987-1999, Dr. Collier was also an Adjunct Professor of the Animal Science Department at the University of Missouri. In September of 1999, Dr. Collier joined the faculty of the Animal Sciences Department, University of Arizona as Professor of Environmental Physiology. From July 1, 2001 to December 31, 2005 he was Head of the Animal Sciences Department. He was Director of the Agricultural Research Complex from 2006-2016. He is currently Professor of Environmental Physiology in the Animal Sciences Department. In 2009 he co-founded Amelgo a research company focused on bringing new technologies to the dairy industry. He is currently Managing Partner and CEO of Amelgo which is located in Covington, Kentucky. Dr. Collier is author or coauthor of 225 peer reviewed journal articles, chapters and reviews, 165 abstracts, 55 popular articles and 10 U.S. Patents. His areas of expertise include environmental and lactation physiology, endocrinology and molecular biology.
- Ph.D. Dairy Science
- University of Illinois, Urbana, Illinois
- Studies on Lactogenesis in the Dairy Cow
- M.S. Zoology
- Eastern Illinois University, Charleston,, Illinois
- Effect of Alloxan Diabetes on Circadian Rhythm of Adrenal Ascorbic Acid in the Rat
- B.S. Zoology
- Eastern Illinois University, Charleston, Illinois
- Monsanto Company (1985 - 1999)
- University of Florida (1976 - 1985)
- Distinguished Alumnus Award
- Eastern Illinois University, Fall 2015
- American Dairy Science Association Fellow Award
- American Dairy Science Association, Summer 2013
- Western Dairy Business Dairy Scientist/Educator of the Year Award
- Western Dairy Business Magazine, Spring 2013
20% teaching, Introduction to Dairy Science, Advanced Dairy Science, Environmental Physiology
80% research, environmental physiology, lactation physiology, endocrinology, nutrition
Intro To Dairy ScienceACBS 220 (Spring 2017)
ResearchPS 900 (Fall 2016)
Adv Dairy Herd ManagemntACBS 472 (Summer I 2016)
ResearchPS 900 (Summer I 2016)
Env Phys Domestic AnimalACBS 409 (Spring 2016)
Env Phys Domestic AnimalACBS 509 (Spring 2016)
Intro To Dairy ScienceACBS 220 (Spring 2016)
Psio+Anat Dom AnimalsACBS 215 (Spring 2016)
ResearchPS 900 (Spring 2016)
- Collier, R. J., & Collier, J. L. (2012). Envionmental Physiology of Livestock. John Wiley & Sons.
- Collier, R. J. (2015). Thermal Biology of Domestic Animals. In Annu. Rev. Anim. Biosci.. Copyright © 2015 by Annual Reviews.More infoThe thermal environment is the most important ecological factor determining the growth, development, and productivity of domesticanimals. Routes of energy exchange (sensible heat and latent heat)between animals and their environment are greatly influenced bybody weight, fat deposition, hair-coat properties, functional activity,and number of sweat glands, as well as the presence or absence ofanatomical respiratory countercurrent heat exchange capability.Differences in these anatomical features across species have led tospecialization of heat exchange. Thermal plasticity and degree of acclimation are critical factors determining the ability of animals to respond to environmental change. Increases in productive capability of domestic animals can compromise thermal acclimation and plasticity, requiring greater investments in housing systems that reduce variability of the thermal environment. The combination of steadily increasing metabolic heat production as domestic animal productivity increases and a rising world temperature poses ongoing and future challenges to maintaining health and well-being of domestic animals.
- Collier, R. J. (2014). Serotonin: A local regulator in the mammary gland epithelium. In Annual Review of Animal Biosciences. DOI: 10.1146/annurev-animal-022513-114227: Annual Reviews.More infoSerotonin (5-hydroxytryptamine, 5-HT) is a very simple molecule that plays key roles in complex communication mechanisms within the animal body. In the mammary glands, serotonin biosynthesis and secretion are induced in response to dilation of the alveolar spaces. Since its discovery several years ago, mammary 5-HT has been demonstrated to perform two homeostatic functions. First, serotonin regulates lactation and initiates the transition into the earliest phases of involution. Second, serotonin is a local signal that induces parathyroid hormone–related peptide (PTHrP), which allows the mammary gland to drive the mobilization of calcium from the skeleton. These processes use different receptor types, 5-HT7 and 5-HT2, respectively. In this review, we provide synthetic perspectives on the fundamental processes of lactation homeostasis and the adaptation of calcium homeostasis for lactation. We analyze the role of the intrinsic serotonin system in the physiological regulation of the mammary glands. We also consider the importance of the mammary serotonin system in pathologies and therapies associated with lactation and breast cancer.
- Collier, R. J., Hall, L. W., & Smith, J. F. (2014). Intensive Livestock Systems For Dairy Cows In: Climate change Impact and Adaptation in Agricultural Systems.. In Climate change Impact and Adaptation in Agricultural Systems. CABI, Publishing. Wallingford ,Oxfordshire, OX10 8DE, UK.
- Collier, R. J., & Roy, K. S. (2012). Regulation of acclimation to envionmental stress. In Envionmental Physiology of Livestock(pp 49-64). John Wiley & Sons.
- Collier, R. J., Elsasser, T. H., Li, C. J., & Shaffer, J. (2012). Effects of envionment on animal health. In Environmental Physiology of Livestock(pp 129-164). John Wiley & Sons.
- Elsasser, T., Li, C., Shaffer, J., & Collier, R. (2012). Effects of environment on animal health: mechanisms and regulatory inputs. In Environmental Physiology of Livestock(pp 129-164). West Sussex, UK: John Wiley & Sons, Inc.More infoEditor(s): Collier, RJ | Collier, JL
- Roy, K., & Collier, R. (2012). Regulation of acclimation to environmental stress. In Environmental Physiology of Livestock(pp 49-64). West Sussex, UK: John Wiley & Sons, Inc.More infoEditor(s): Collier, RJ | Collier, JLThis chapter contains sections titled: What Is Acclimation?Adaptation: Bos indicus versus Bos taurusWhat Are the Stages of Acclimation?ConclusionReferences
- Hall, L. W., Dunshea, F. R., Allen, J. D., Rungruang, S., Collier, J. L., Long, N. M., & Collier, R. J. (2016). Evaluation of dietary betaine in lactating Holstein cows subjected to heat stress. Journal of dairy science, 99(12), 9745-9753.More infoBetaine (BET), a natural, organic osmolyte, improves cellular efficiency by acting as a chaperone, refolding denatured proteins. To test if dietary BET reduced the effect of heat stress (HS) in lactating dairy cows, multiparous, lactating Holstein cows (n=24) were blocked by days in milk (101.4±8.6 d) and randomly assigned to 1 of 3 daily intakes of dietary BET: the control (CON) group received no BET, mid intake (MID) received 57mg of BET/kg of body weight, and high dose (HI) received 114mg of BET/kg of body weight. Cows were fed twice daily and BET was top-dressed at each feeding. Cows were milked 2 times/d and milk samples were taken daily for analysis. Milk components, yield, feed intake, and water intake records were taken daily. Rectal temperature and respiration rate were taken 3 times/d at 0600, 1400, and 1800h. Cows were housed in environmentally controlled rooms and were allowed acclimation for 7d at thermoneutral (TN) conditions with a mean temperature-humidity index of 56.6. Cows were then exposed to 7d of TN followed by 7d of HS represented by a temperature-humidity index of 71.5 for 14d. This was followed by a recovery period of 3d at TN. Dietary BET increased milk yield during the TN period. No differences were found between BET and CON in total milk production or milk composition during HS. The increase in water intake during HS was not as great for cows fed BET compared with controls. The cows on CON diets had higher p.m. respiration rate than both MID and HI BET during HS, but lower rectal temperature compared with BET. No difference was found in serum glucose during TN, but cows given HI had elevated glucose levels during HS compared with CON. No differences were found in serum insulin levels between CON and BET but an intake by environment interaction was present with insulin increasing in HI-treated lactating dairy cows during HS. The heat shock response [heat shock protein (HSP) 27 and HSP70] was upregulated in bovine mammary epithelial cells in vitro. Blood leukocyte HSP27 was downregulated at the HI dose under TN conditions and HSP70 was upregulated at the HI dose and this effect was increased by HS. No effect was seen with the MID dose with HSP27 or HSP70. The lack of effect of BET at MID may be associated with uptake across the gut. We conclude that BET increased milk production under TN conditions and was associated with reduced feed and water intake and slightly increased body temperatures during HS of cows fed BET. The effect of BET on milk production was lost during HS with HI BET, whereas serum glucose levels increased during HS.
- Collier, R. J. (2015). A comparison of 2 evaporative cooling systems on a commercial dairy farm in Saudi Arabia.. journal of Dairy Science, 98(12), 8710-22. doi:doi: 10.3168/jds.2015-9616More infoEfficacy of 2 cooling systems (Korral Kool, KK, Korral Kool Inc., Mesa, AZ; FlipFan dairy system, FF, Schaefer Ventilation Equipment LLC, Sauk Rapids, MN) was estimated utilizing 400 multiparous Holstein dairy cows randomly assigned to 1 of 4 cooled California-style shade pens (2 shade pens per cooling system). Each shaded pen contained 100 cows (days in milk=58±39, milk production=56±18 kg/d, and lactation=3±1). Production data (milk yield and reproductive performance) were collected during 3mo (June-August, 2013) and physiological responses (core body temperature, respiration rates, surface temperatures, and resting time) were measured in June and July to estimate responses of cows to the 2 different cooling systems. Water and electricity consumption were recorded for each system. Cows in the KK system displayed slightly lower respiration rates in the month of June and lower surface temperatures in June and July. However, no differences were observed in the core body temperature of cows, resting time, feed intake, milk yield, services/cow, and conception rate between systems. The FF system used less water and electricity during this study. In conclusion, both cooling systems (KK and FF) were effective in mitigating the negative effects of heat stress on cows housed in arid environments, whereas the FF system consumed less water and electricity and did not require use of curtains on the shade structure
- Collier, R. J. (2015). Environmental heat stress modulates thyroid status and its response to repeated endotoxin challenge in steers.. Domest. Anim. Endocrinol, 52, 43-50. doi:10.1016/j.domaniend.2015.02.001More infoThe objective of this study was to evaluate in cattle, the effects of acute exposure to a heat stress (HS) environment on the status of the pituitary (thyrotropin, TSH)-thyroid (thyroxine, T4)-peripheral tissue T4 deiodination (type 1 5'-deiodinase [D1]; triiodothyronine [T3]; reverse-triiodothyronine [rT3]) axis, and the further response of this pituitary-thyroid-peripheral tissue axis (PTTA) to perturbation caused by the induction of the proinflammatory innate immune state provoked by the administration of gram-negative bacteria endotoxin (lipopolysaccharide [LPS]). Ten steers (318 ± 49kg body weight) housed in controlled environment chambers were subjected to either a thermoneutral (TN: constant 19°C) or HS temperature conditions (cyclical daily temperatures: 32.2°C-40.0°C) for a total period of 9d. To minimize the effects of altered plane of nutrition due to HS, steers in TN were pair-fed to animals in HS conditions. Steers received 2 LPS challenges 3d apart (LPS1 and LPS2; 0.2μg/kg body weight, intravenously, Escherichia coli 055:B5) with the first challenge administered on day 4 relative to the start of the environmental conditioning. Jugular blood samples were collected at 0, 1, 2, 4, 7, and 24h relative to the start of each LPS challenge. Plasma TSH, T4, T3, and rT3 were measured by radioimmunoassay. Liver D1 activity was measured in biopsy samples collected before the LPS1 (0h) and 24h after LPS2. Before the start of LPS1, HS decreased (P < 0.01 vs TN) plasma TSH (40%), T4 (45.4%), and T3 (25.9%), but did not affect rT3 concentrations. In TN steers, the LPS1 challenge decreased (P < 0.01 vs 0h) plasma concentrations of TSH between 1 and 7h and T4 and T3 at 7 and 24h. In HS steers, plasma TSH concentrations were decreased at 2h only (P < 0.05), whereas plasma T3 was decreased at 7 and 24h (P < 0.01). Whereas plasma T4 concentrations were already depressed in HS steers at 0h, LPS1 did not further affect the levels. Plasma rT3 concentrations were increased in all steers at 4, 7, and 24h after LPS1 (P < 0.01). The patterns of concentration change of T4, T3, and rT3 during LPS2 mirrored those observed in LPS1; the responses in plasma TSH were of smaller magnitude than those incurred after LPS1. The LPS challenges reduced (P < 0.01) hepatic activity of D1 in all animals but no differences were observed between steers subjected to TN or HS environment. The data are consistent with the concept that acute exposure of cattle to a HS environment results in the depression of the pituitary and thyroid components of the PTTA, whereas a normal capacity to generate T3 from T4 in the liver is preserved. The data also suggest that LPS challenge further suppresses all components of the PTTA including liver T3 generation, and these PTTA perturbations are more pronounced in steers that encounter a HS exposure.
- Collier, R. J. (2015). Evaluation of conductive cooling of lactating dairy cows under controlled environmental conditions.. Journal of Dairy Science, 98(3), 1759-71. doi:doi: 10.3168/jds.2014-8583More infoCooling systems used to reduce heat stress in dairy operations require high energy, water usage, or both. Steady increases in electricity costs and reduction of water availability and an increase in water usage regulations require evaluation of passive cooling systems to cool cows and reduce use of water and electricity. A study was conducted to evaluate the use of heat exchangers buried 25 cm below the surface as components in a conductive system for cooling cows. Six cows were housed in environmentally controlled rooms with tie-stall beds, which were equipped with a heat exchanger and filled with 25 cm of either sand or dried manure. Beds were connected to supply and return lines and individually controlled. Two beds (one per each kind of bedding material) constituted a control group (water off), and the other 4 (2 sand and 2 dried manure) used water at 7°C passing through the heat exchangers (water on). The experiment was divided in 2 periods of 40 d, and each period involved 3 repetitions of 3 different climates (hot and dry, thermo neutral, and hot and humid). Each cow was randomly assigned to a different treatment after each repetition was over. Sand bedding remained cooler than dried manure bedding in all environments and at all levels of cooling (water on or off). Bed temperatures were lower and heat flux higher during the bed treatment with sand and water on. We also detected a reduction in core body temperatures, respiration rates, rectal temperatures, and skin temperatures of those cows during the sand and water on treatment. Feed intake and milk yield numerically increased during the bed treatment with sand and water on for all climates. No major changes were observed in the lying time of cows or the composition of the milk produced. We conclude that use of heat exchangers is a viable adjunct to systems that employ fans, misters, and evaporative cooling methods to mitigate effects of heat stress on dairy cows. Sand was superior to dried manure as a bedding material in combination with heat exchangers
- Collier, R. J. (2015). Milk yield differences between 1× and 4× milking are associated with changes in mammary mitochondrial number and milk protein gene expression, but not mammary cell apoptosis or SOCS gene expression.. Journal of Dairy Science, 98(7), 4439-48. doi:10.3168/jds.2014-8917More infoMilking frequency is known to affect milk production and lactation persistence in dairy cows. Despite this, the mechanisms underlying this effect are only partially understood. Previous work in dairy cows examining increases in milk yield due to increased milking frequency have identified changes in apoptosis and expression of genes regulating cytokine signaling. In addition, changes in mitochondrial biogenesis and function have been suggested to play a role during the lactation cycle in regulating milk production. The goal of this study was to test the hypothesis that, when maintained over an entire lactation, extreme differences in milking frequency would be reflected in differences in apoptosis, mammary mitochondrial number, and the mammary expression of genes known to inhibit cytokine signaling. Primiparous Holstein cows (n=6) were assigned to the study 40d before parturition after which 1 udder half was milked once daily (1×) and the other 4 times daily (4×) Mammary biopsies were collected at 15, 60, 120, and 230d of lactation. Average milk yield from the 4× side was 3 times higher than from the 1× side. Analysis of milk composition revealed that protein, lactose, and solids-not-fat percentages were lower in 1× than 4× udder halves. Mammary cell apoptosis was not affected by milking frequency. Mammary cell mitochondrial number, as estimated by succinate dehydrogenase staining, was higher in early lactation, decreasing as days in milk increased, and with increased milking frequency. Although mammary expression of α-lactalbumin (LALBA) and β-casein (CSN2) was significantly increased in 4× glands, the expression of suppressors of cytokine signaling were similar between 1×- and 4×-milked halves. These results support the conclusion that changes in milk production in response to extreme differences in milking frequency may be related to alterations in mitochondrial number and lactose synthesis, but not apoptosis
- Collier, R. J. (2015). Short communication: Effect of cross ventilation with or without evaporative pads on core body temperature and resting time of lactating cows.. Journal of Dairy Science, 99(1), 1-6. doi:doi:10.3168/jds.2015-9624More infoA trial was performed to assess the effect of evaporative pads on core body temperature (CBT) and lying behavior of lactating Holstein cows housed in cross-ventilated freestall facilities in a humid environment. This trial was undertaken in 2 barns equipped with (EP) or without (NP) evaporative pads. Each facility had 4 pens, 1 baffle/pen, and a nominal width of 122 m. Stocking density was higher (123.4 vs. 113.1%) and freestalls were slightly shorter (2.3 vs. 2.4 m) and narrower (1.16 vs. 1.21 m) in EP compared with NP barns. In each pen, lying behavior of 20 cows was monitored using electronic data loggers that recorded at 1-min intervals. A subset (n = 14) of these cows within each pen were also fitted with temperature loggers attached to blank controlled intravaginal drug release devices to determine CBT every 5 min. Ambient conditions were collected every 15 min. Individual cow lying duration and lying bouts were assessed for each cow, as well as time spent standing and CBT within the following categories: CBT 38.6, >38.9, >39.2, >39.4, and >39.7°C. These variables were analyzed using pen as the experimental unit, with cow and day as additional random effects. The average maximum ambient conditions over the 9 d were 25°C and 78.74% relative humidity. No differences were observed in lying duration and number of lying bouts over the 9-d period, with overall means of 696 ± 31 min/d and 12.6 ± 0.5 bouts/d. The EP cows spent 170 min/d longer with a CBT 39.2°C than did NP cows. Cooling with evaporative pads tended to increase time spent lying with a CBT >8.6°C and lying bouts/d for EP cows versus NP cows. Results from this trial show that even under mild heat stress, evaporative cooling in cross-ventilated facilities can decrease CBT and tended to increase lying time
- Collier, R. J. (2014). . Effect of core body temperature, time of day and comate conditions on behavioral patterns of lactating dairy cows experiencing mild to moderate heat stress.. Journal of Dairy Science, 98, 118-127.More infoExcessive standing in heat-stressed cows can negatively affect overall production. An increase in core body temperature (CBT) positively influenced the likelihood for cows to stand, with a 50% likelihood reached at a CBT of 38.93°C. Cows stood for longer periods during the afternoon (1200 to 1800 h) compared to other periods of the day. Standing durations increased and lying durations decreased as CBT increased. The results of this study indicate that lying behavior of heat-stressed cows is correlated to their CBT.
- Collier, R. J. (2014). Effects of source and extent of tropical adaptation in beef cattle pre and post-weaning calf performances.. Professional Animal Scientist.
- Collier, R. J. (2014). Growth and reproductive performances in F1 crossbred heifers from Hereford, Braford and Bonsmara sires and Angus and Brangus dams.. Professional Animal Scientist, 30(3), 342-353.More infoThe objective of this research was to evaluate source and extent of tropical adaptation affecting heifer BW and productivity traits. The F1 heifers with Brangus (BN) dams were sired by Braford (BFBN; n = 44), Hereford (HEBN; n = 29), and Bonsmara (BOBN; n = 58) sires. The F1 heifers with Angus (AN) dams were sired by Hereford (HEAN; n = 32) and Bonsmara (BOAN, n = 40) sires. The F1 heifer breeds did not differ (P > 0.22) for pregnancy and weaning rate. Calving rate was similar (P > 0.26) among F1 heifer breed types, but there was a tendency (P < 0.10) for calving rate to be greater for HEBN compared with BOBN F1 heifers. Live BW at weaning of their first calf was similar (P > 0.17) for BFBN and HEBN F1 cows and for HEBN and BOBN F1 cows but was greater (P < 0.05) for BFBN compared with BOBN and for BOAN compared with HEAN. The F1 cows with BN dams were heavier (P < 0.01) and had lower (P < 0.05) BCS at weaning than F1 cows with AN dams. Calf adjusted 205-d BW was similar (P > 0.25) among BFBN, HEBN, and BOBN F1 cows but was greater (P < 0.01) for BOAN compared with HEAN and for BN compared with AN granddams. In the present study, there were differences in heifer BW and offspring growth traits among F1 breed types, but there was not a distinct overall advantage (P > 0.35) of any particular breed type based on calf:dam weaning BW ratios.
- Collier, R. J. (2014). Update on human health concerns of recombinant bovine somatotropin (rbST) use in dairy cows. Journal of Dairy Science.
- Rungruang, S., Collier, J. l., Rhoads, R. P., Baumgard, L. H., Deveth, M. J., & Collier, R. J. (2014). . A dose response evaluation of rumen-protected niacin (RPN) in heat-stressed lactating Holstein Cows. Journal of Dairy Science.
- St. Pierre, N. R., Millikin, G. A., Bauman, D. E., Hogan, J. S., Collier, R. J., Shearer, J. K., Smith, K. L., & Thatcher, W. W. (2014). Production and health effects of sometribove zinc suspension (recombinant bovine somatotropin) in lactating dairy cows. JAVMA. Journal American Veterinary Medicine Association.
- Wyatt, W. E., Collier, R. J., Blouin, D. C., & Scaglia, C. (2014). Effects of source and extent of tropical adaptation in beef cattle pre and post-weaning calf performances.. Professional Animal Scientist.
- Anderson, S. D., Bradford, B. J., Harner, J. P., Tucker, C. B., Choi, C. Y., Allen, J. D., Hall, L. W., Rungruang, S., Collier, R. J., & Smith, J. F. (2013). Effects of adjustable and stationary fans with misters on core body temperature and lying behavior of lactating dairy cows in a semiarid climate. Journal of Dairy Science, 96(7), 4738-4750.More infoPMID: 23684043;Abstract: Cows readily seek shade to reduce solar heat load during periods of high ambient temperature. Typically, auxiliary cooling systems are oriented to maximize cooling for shaded cows. However, when a shade structure is oriented north-south, stationary fan and mister cooling systems are unable to track shade as the sun's angle shifts throughout the day, and thus can become ineffective. The FlipFan Dairy Cooling System (Schaefer Ventilation Equipment, Sauk Rapids, MN) employs fans and misters that follow shade and compensate for wind speed by rotating on a horizontal axis. Multiparous, lactating Holstein cows (n = 144) on a commercial dairy in Arizona were cooled by a fixed system comprised of stationary fans and misters acting as control or the adjustable FlipFan operated for 16.5 h/d (0830 to 0100 h). Core body temperatures (CBT) of 64 cows (4 pens/treatment; 8 cows/pen; 6. d) and lying behavior of 144 cows (4 pens/treatment; 18 cows/pen; 5. d) were collected by intravaginal and leg data loggers, respectively. Cows were balanced by milk production, blocked by days in milk, and randomly assigned to pen within block. Pen was the experimental unit. In a second experiment, isothermal maps were developed using a fixed system of thermal data loggers arranged in the shaded areas of the pens at different times of day and were analyzed for differences in the temperature-humidity index (THI) achieved by each cooling treatment. Ambient conditions consisted of a mean temperature of 33.0°C, mean relative humidity of 40.3%, and mean THI of 80.2. Mean 24-h CBT for FlipFan was lower than control (38.9 vs. 39.1 ± 0.04°C). A treatment × time interaction was observed in which CBT of FlipFan was 0.4°C lower than control from 0600 to 0800. h and 1500 to 1600. h. Cows cooled by FlipFan spent more time lying down compared with those cooled by control (9.5 vs. 8.6 h/d). Cows under FlipFan had more frequent lying bouts than did those under control (12.8 vs. 10.7 bouts/d). Lower CBT and decreased standing time are consistent with the findings of other studies when ambient heat load was reduced. In the second experiment, the FlipFan system achieved a lower THI in the morning and evening (5.9 and 1.7%, respectively), and the THI also tended to be 0.8% lower in the afternoon compared with that of control. Results indicate that FlipFan is more effective than a stationary fan and mister system at decreasing CBT, increasing lying time and bouts, and providing a more desirable microenvironment for cows throughout the day in a semiarid environment. © 2013 American Dairy Science Association.
- Anderson, S., Bradford, B., Harner, J., Tucker, C., Choi, C., Allen, J., Hall, L., Rungruang, S., Rahjapaksha, E., Collier, R., & Smith, J. (2013). Effects of adjustable and stationary fans with misters on core body temperature and resting behavior of lactating dairy cows in a semi-arid environment. J. Dairy Sci, 96(7), 4738–4750.More infoCows readily seek shade to reduce solar heat load during periods of high ambient temperature. Typically, auxiliary cooling systems are oriented to maximize cooling for shaded cows. However, when a shade structure is oriented north-south, stationary fan and mister cooling systems are unable to track shade as the sun’s angle shifts throughout the day, and thus can become ineffective. The FlipFan Dairy Cooling System (Schaefer Ventilation Equipment, Sauk Rapids, MN) employs fans and misters that follow shade and compensate for wind speed by rotating on a horizontal axis. Multiparous, lactating Holstein cows (n = 144) on a commercial dairy in Arizona were cooled by a fixed system comprised of stationary fans and misters acting as control or the adjustable FlipFan operated for 16.5 h/d (0830 to 0100 h). Core body temperatures (CBT) of 64 cows (4 pens/treatment; 8 cows/pen; 6 d) and lying behavior of 144 cows (4 pens/treatment; 18 cows/pen; 5 d) were collected by intravaginal and leg data loggers, respectively. Cows were balanced by milk production, blocked by days in milk, and randomly assigned to pen within block. Pen was the experimental unit. In a second experiment, isothermal maps were developed using a fixed system of thermal data loggers arranged in the shaded areas of the pens at different times of day and were analyzed for differences in the temperature-humidity index (THI) achieved by each cooling treatment. Ambient conditions consisted of a mean temperature of 33.0°C, mean relative humidity of 40.3%, and mean THI of 80.2. Mean 24-h CBT for FlipFan was lower than control (38.9 vs. 39.1 ± 0.04°C). A treatment × time interaction was observed in which CBT of FlipFan was 0.4°C lower than control from 0600 to 0800 h and 1500 to 1600 h. Cows cooled by FlipFan spent more time lying down compared with those cooled by control (9.5 vs. 8.6 h/d). Cows under FlipFan had more frequent lying bouts than did those under control (12.8 vs. 10.7 bouts/d). Lower CBT and decreased standing time are consistent with the findings of other studies when ambient heat load was reduced. In the second experiment, the FlipFan system achieved a lower THI in the morning and evening (5.9 and 1.7%, respectively), and the THI also tended to be 0.8% lower in the afternoon compared with that of control. Results indicate that FlipFan is more effective than a stationary fan and mister system at decreasing CBT, increasing lying time and bouts, and providing a more desirable microenvironment for cows throughout the day in a semiarid environment.
- Deaver, S. E., Hoyer, P. B., Dial, S. M., Field, M. E., Collier, R. J., & Rhoads, M. L. (2013). Localization of ghrelin and its receptor in the reproductive tract of Holstein heifers. Journal of Dairy Science, 96(1), 150-157.More infoPMID: 23141832;Abstract: The aim of this experiment was to localize the mRNA and protein of ghrelin and its active receptor, growth hormone secretagogue 1A (GHS-R1A), within the reproductive tract of dairy cattle. Ghrelin is an orexigenic hormone that has been identified as a potent regulator of energy homeostasis. Recent evidence suggests that ghrelin may also serve as a metabolic signal to the reproductive tract. Ghrelin and GHS-R1A have been identified in the reproductive tract of several species, including humans, mice, and rats. However, ghrelin and GHS-R1A expression have not been described within bovine reproductive tissues. Therefore, the ampulla, isthmus, uterine body, corpus luteum, and follicles were harvested from 3 Holstein heifers (15.91±0.07. mo of age) immediately following exsanguination. Duodenum and hypothalamus were collected as positive controls for ghrelin and GHS-R1A, respectively. Tissues were fixed in 10% formalin and embedded in paraffin for microscopy. Additional samples were stored at -80°C for detection of mRNA. Ghrelin and GHS-R1A mRNA and protein were observed in all tissue types within the reproductive tract of dairy heifers; however, expression appeared to be cell specific. Furthermore, ghrelin protein appeared to be localized to the cytoplasm, whereas GHS-R1A protein was found on the plasma membrane. Within the reproductive tissues, ghrelin mRNA and protein were most abundantly expressed in the ampulla of the oviduct. Concentrations of GHS-R1A were lower than those of ghrelin but differed between tissues. This is one of the first studies to provide molecular evidence for the presence of ghrelin and GHS-R1A within the entire reproductive tract. However, implications for fertility remain to be determined. © 2013 American Dairy Science Association.
- Dunshea, F. R., Leury, B. J., Fahri Fahri, A., DiGiacomo, K., Hung, A., Chauhan, A. S., Clark, I. J., Collier, R. J., Little, C. S., Baumgard, L. H., & Gaughan, J. B. (2013). Amelioration of thermal stress impacts in dairy cows. Animal Production Science, 53(01), 965-975.More infoHeat stress negatively impacts on a variety of animal production parameters. Advances in management strategies have alleviated some of the negative impacts of thermal stress on farm animals, but production continues to markedly decrease during heat events in summer, particularly in dairy cattle. In this paper we introduce a Dairy Risk Assessment Program (DRAP). The DRAP is a user-friendly software package designed to assist users in predicting heat loads in dairy cow herds. DRAP was developed over three Australian summers using climatic data (temperature, humidity, solar radiation and wind speed), cow production data (milk yield and milk quality), and physiological data (respiration rate and body temperature). The data were used to develop mathematical algorithms which can predict animal response to climatic variables. This software package is designed to be used by the dairy industry to better manage cows during times of elevated environmental temperatures by equipping producers, managers, and dairy industry personnel with Dairy Heat Load Index (DHLI) values which were calculated based upon site information, stock characteristics, management practices, and mitigation variables specific to their dairy production unit. When a heat event is imminent producers can then introduce management strategies such as providing shade or additional water troughs or implementation of nutritional strategies. Some of these nutritional strategies include dietary chromium picolinate, betaine and antioxidant supplementation or altering the rate of starch fermentation. These nutritional strategies are discussed at some length in this paper.
- Dunshea, F. R., Leury, B. J., Fahri, F., Digiacomo, K., Hung, A., Chauhan, S., Clarke, I. J., Collier, R., Little, S., Baumgard, L., & Gaughan, J. B. (2013). Amelioration of thermal stress impacts in dairy cows. Animal Production Science, 53(9), 965-975.More infoAbstract: Heat stress negatively impacts on a variety of animal production parameters. Advances in management strategies have alleviated some of the negative impacts of thermal stress on farm animals, but production continues to markedly decrease during heat events in summer, particularly in dairy cattle. In this paper we introduce a Dairy Risk Assessment Program (DRAP). The DRAP is a user-friendly software package designed to assist users in predicting heat loads in dairy cow herds. DRAP was developed over three Australian summers using climatic data (temperature, humidity, solar radiation and wind speed), cow production data (milk yield and milk quality), and physiological data (respiration rate and body temperature). The data were used to develop mathematical algorithms which can predict animal response to climatic variables. This software package is designed to be used by the dairy industry to better manage cows during times of elevated environmental temperatures by equipping producers, managers, and dairy industry personnel with Dairy Heat Load Index (DHLI) values which were calculated based upon site information, stock characteristics, management practices, and mitigation variables specific to their dairy production unit. When a heat event is imminent producers can then introduce management strategies such as providing shade or additional water troughs or implementation of nutritional strategies. Some of these nutritional strategies include dietary chromium picolinate, betaine and antioxidant supplementation or altering the rate of starch fermentation. These nutritional strategies are discussed at some length in this paper. © CSIRO 2013.
- Field, M. E., Deaver, S. E., Rhoads, R. P., Collier, R. J., & Rhoads, M. L. (2013). Effects of prolonged nutrient restriction on baseline and periprandial plasma ghrelin concentrations of postpubertal Holstein heifers. Journal of Dairy Science, 96(10), 6473-6479.More infoPMID: 23958007;Abstract: Objectives of this study were to measure both daily and periprandial plasma ghrelin concentrations of postpubertal Holstein heifers during prolonged undernutrition. Following an acclimation period, Holstein heifers [n = 10; 339.5 ± 8.6. kg of body weight (BW)] were fed ad libitum [well fed (WF); n = 5] or restricted to 50% of ad libitum intake [underfed (UF); n = 5) for 8. wk. Body condition scores (BCS) were recorded at the beginning and end of the treatment period, and weekly measurements of BW, plasma ghrelin, progesterone, and nonesterified fatty acids (NEFA) concentrations were obtained. Ovarian follicular and luteal structures were measured twice weekly via transrectal ultrasonography. Plasma ghrelin concentrations were also measured during a periprandial window bleed conducted at the end of the experiment. During the window bleed, samples were collected every 15. min between 0500 and 0900. h, with feed offered at 0700. h. Underfed heifers lost BW and BCS, whereas WF heifers gained weight and either increased or maintained BCS. Chronic underfeeding increased circulating ghrelin and NEFA concentrations. By wk 4 of the treatment period, circulating ghrelin concentrations of the UF heifers reached a plateau. Periprandial fluctuations in ghrelin concentrations were apparent as plasma ghrelin concentrations changed over time. Overall differences in periprandial plasma ghrelin concentrations were primarily due to prefeeding effects of plane of nutrition. Plasma ghrelin concentrations and change in BCS were negatively correlated such that heifers that lost the most BCS had the highest concentrations of circulating ghrelin. Two of the 5 UF heifers became anestrus by wk 3 of the treatment period. Despite being of similar age, the heifers that became anestrus had lower BW and plasma ghrelin concentrations than the UF heifers that continued to ovulate. In the current experiment, long-term undernutrition elicited ghrelin responses similar to those reported for shorter durations of nutrient restriction in cattle and other ruminants. These results demonstrate that plane of nutrition is a chronic regulator of plasma ghrelin concentrations, and that these concentrations can be experimentally manipulated in postpubertal heifers for up to 8. wk with no evidence of an adaptive response. © 2013 American Dairy Science Association.
- Wyatt, W. E., Collier, R. J., Bouin, D. C., Scaglia, C., & Collier, J. L. (2013). Pre- and postweaning calf performances in crossbred cattle from Hereford, Braford, and Bonsmara sires and Angus and Brangus dams. Professional Animal Scientist, 29, 621-631.More infoGrowth traits were evaluated on 560 calves (288 male and 272 female calves) to determine the source and extent of tropical adaptation affecting calf preweaning and postweaning growth performances. Calves with Brangus dams were sired by Braford (BFBN; n = 115; 38% Brahman), Hereford (HEBN; n = 92; 19% Brahman), and Bonsmara (BOBN; n = 139; 19% Brahman and 31% Africander) sires. Calves with Angus (AN) dams were sired by Hereford (HEAN; n = 95) and Bonsmara (BOAN, n = 119; 31% Africander) sires. Growth performances of BFBN and HEBN calves were similar (P > 0.15) for an array of growth traits. However, BFBN and HEBN either tended to (P < 0.10) or had (P < 0.05) greater adjusted birth BW, postweaning ADG, and adjusted 452-d BW when compared with BOBN. Calves with AN dams and Bonsmara sires had greater preweaning ADG (P < 0.05), adjusted 205-d BW (P < 0.01), and adjusted 452-d BW (P < 0.01) than HEAN calves. Among calves with Brangus dams, extent (BFBN vs. HEBN) of tropical adaptation was not important in terms of growth, but source (BFBN vs. BOBN and HEBN vs. BOBN) of tropical adaptation did not favor those calves with Africander breeding. However, for calves with AN dams, the use of Bonsmara sires (BOAN) imparted a growth advantage relative to the HE sires (HEAN). It is important that tropical adaptation, in terms of Brahman and Africander breeding, be imparted to the calf directly but more importantly, that Brahman breeding is imparted maternally
- Wyatt, W. E., Lawrence, T. E., Collier, R. J., Blouin, D. C., Scaglia, C., & Collier, J. L. (2013). Feedlot performance, carcass merit, and meat tenderness in crossbred cattle from Herefored, Braford, and Bonsmara sires and Angus and Brangus dams.. Professional Animal Scientist, 29, 632-644..More infoThe objective of this research was to evaluate the source and extent of tropical adaptation affecting feedlot and carcass traits. Calves of Brangus (BN) dams were sired by Braford (BFBN; n = 63; 38% Brahman), Hereford (HEBN; n = 38; 19% Brahman), and Bonsmara (BOBN; n = 53; 19% Brahman and 31% Africander) sires. Calves of Angus (AN) dams were sired by Hereford (HEAN; n = 38) and Bonsmara (BOAN; n = 45; 31% Africander) sires. Carcass yield and LM area were greater (P < 0.05) for HEBN compared with BFBN. Whereas BFBN had greater (P < 0.01) backfat and empty body fat than the BOBN counterparts, the latter had greater (P < 0.01) LM area. Contrasting HEBN and BOBN, HEBN were heavier (P < 0.05) and fatter (P < 0.05). However, BOBN were more heavily muscled (P < 0.05) and deposited more internal fat (P < 0.05). The BOAN steers were heavier (P < 0.05) upon feedlot arrival than HEAN steers. Steers of Brangus (BN) dams were heavier (P < 0.01), but steers of Angus (AN) dams exhibited greater (P < 0.01) marbling scores. There were neither sire-breed nor dam-breed differences (P > 0.15) in Warner-Bratzler shear force values. Presence of Brahman breeding (BN) in the dam breed positively affected weight traits, whereas absence of Brahman breeding (AN) positively affected carcass merit traits. In terms of sire breed contributions, neither extent nor source of tropical adaptation provided a distinct overall advantage in this study.
- Zimbelman, R. B., Collier, R. J., & Bilby, T. R. (2013). Effects of utilizing rumen protected niacin on core body temperature as well as milk production and composition in lactating dairy cows during heat stress. Animal Feed Science and Technology, 180(1-4), 26-33.More infoAbstract: Niacin has been shown to increase resistance to thermal stress in cattle by increasing evaporative heat loss in vivo and cellular heat shock response by increasing gene expression of heat shock proteins 27 and 70 during thermal stress in vitro. To determine effects of feeding encapsulated niacin on vaginal temperature, milk yield and composition, a total of 198 primiparous and 229 multiparous lactating Holstein cows were randomly assigned in a crossover design to either control (no niacin additive, n=213) or niacin (NIA; cows supplemented with 12. g/d/cow of an encapsulated niacin, n=214). Treatments were balanced for days in milk (DIM), milk yield, and parity prior to the start of the study, which was conducted between August 7th and October 7th, 2007 on a commercial dairy in Arizona (USA). Cows remained on their original treatment for 30. d (period 1) and then switched to the other treatment on day 31 and continued until day 60 (period 2). Vaginal temperatures were recorded using temperature data loggers attached to a blank controlled internal drug release device and inserted into a random sub-sample of 16 cows from each pen with similar days in milk, milk yields and parity for 8. d. Effects of heat stress were more severe in period 1 due to a higher temperature humidity index compared with period 2. Dry matter intakes did not differ by treatment or period. Both period and NIA affected vaginal temperatures with NIA reducing vaginal temperatures and period 1 having higher vaginal temperatures compared with period 2. In addition, vaginal temperatures decreased (P
- Zimbleman, R., Collier, R., & Bilby, T. (2013). Effects of feeding encapsulated niacin on core Body temperature, milk production and composition in lactating dairy cows during heat stress. Anim Feed Sci and Technol, 180(1-4), 55-65.More infoNiacin has been shown to increase resistance to thermal stress in cattle by increasing evaporative heat loss in vivo and cellular heat shock response by increasing gene expression of heat shock proteins 27 and 70 during thermal stress in vitro. To determine effects of feeding encapsulated niacin on vaginal temperature, milk yield and composition, a total of 198 primiparous and 229 multiparous lactating Holstein cows were randomly assigned in a crossover design to either control (no niacin additive, n = 213) or niacin (NIA; cows supplemented with 12 g/d/cow of an encapsulated niacin, n = 214). Treatments were balanced for days in milk (DIM), milk yield, and parity prior to the start of the study, which was conducted between August 7th and October 7th, 2007 on a commercial dairy in Arizona (USA). Cows remained on their original treatment for 30 d (period 1) and then switched to the other treatment on day 31 and continued until day 60 (period 2). Vaginal temperatures were recorded using temperature data loggers attached to a blank controlled internal drug release device and inserted into a random sub-sample of 16 cows from each pen with similar days in milk, milk yields and parity for 8 d. Effects of heat stress were more severe in period 1 due to a higher temperature humidity index compared with period 2. Dry matter intakes did not differ by treatment or period. Both period and NIA affected vaginal temperatures with NIA reducing vaginal temperatures and period 1 having higher vaginal temperatures compared with period 2. In addition, vaginal temperatures decreased (P
- Collier, R. J., Annen-Dawson, E., & Pezeshki, A. (2012). Effects of continuous lactation and short dry periods on mammary function and animal health. Animal, 6(3), 403-414.More infoPMID: 22436219;Abstract: The dry period is required to facilitate cell turnover in the bovine mammary gland in order to optimize milk yield in the next lactation. Traditionally, an 8-week dry period has been a standard management practice for dairy cows based on retrospective analyses of milk yields following various dry period lengths. However, as milk production per cow has increased, transitioning cows from the nonlactating state to peak milk yield has grown more problematic. This has prompted new studies on dry period requirements for dairy cows. These studies indicate a clear parity effect on dry period requirement. First parity animals require a 60-day dry period, whereas lactations following later parities demonstrate no negative impact with 30-day dry period or even eliminating the dry period when somatotropin (ST) is also used to maintain milk yields. Shortened dry periods in first parity animals were associated with reduced mammary cell turnover during the dry period and early lactation and increased numbers of senescent cells and reduced functionality of lactating alveolar mammary cells postpartum. Use of ST and increased milking frequency postpartum reduced the impact of shortened dry periods. The majority of new intramammary infections occur during the dry period and persist into the following lactation. There is therefore the possibility of altering mastitis incidence by modifying or eliminating the dry period in older parity animals. As the composition of mammary secretions including immunoglobulins may be reduced when the dry period is reduced or eliminated, there is the possibility that the immune status of cows during the peripartum period is influenced by the length of the dry period. © Copyright The Animal Consortium 2011.
- Collier, R. J., Hernandez, L. L., & Horseman, N. D. (2012). Serotonin as a homeostatic regulator of lactation. Domestic Animal Endocrinology, 43(2), 161-170.More infoPMID: 22608139;Abstract: Serotonin (5-HT), a neurotransmitter produced in mammary epithelial cells (MECs), acts via autocrine-paracrine mechanisms on MECs to regulate milk secretion in a variety of species. Recent studies in dairy cows reported that 5-HT ligands affect milk yield and composition. We determined the mRNA expression of bovine 5-HT receptor (5-HTR) subtypes in bovine mammary tissue (BMT) and cultured bovine MECs. We then used pharmacologic agents to evaluate functional activities of 5-HTR subtypes. The mRNAs for five receptor isoforms (5-HTR1B, 5-HTR2A, 5-HTR2B, 5-HTR4, and 5-HTR7) were identified by conventional reverse transcription PCR, real-time PCR, and in situ hybridization in BMT. In addition to luminal MEC expression, 5-HTR4 was expressed in myoepithelium, and 5-HTR1B, HTR2A, and HTR2B were expressed in small mammary blood vessels. Studies to date report that there are multiple 5-HTR isoforms in mammary tissue of rodents, humans, and cattle. Inhibition of the 5-HT reuptake transporter with selective 5-HT reuptake inhibitors (SSRIs) disrupted tight junctions and decreased milk protein mRNA expression in mouse, human, and bovine mammary cells. Selective 5-HT reuptake inhibitors act to increase the cellular exposure to 5-HT by preventing reuptake of 5-HT by the cell and eventual degradation. Increasing 5-HT concentration in milk via inhibiting its reuptake (SSRI), or by increasing the precursor for 5-HT synthesis 5-hydroxytryptophan, accelerated decline in milk synthesis at dry-off. We conclude that the 5-HT system in mammary tissue acts as a homeostatic regulator of lactation. © 2012 Elsevier Inc.
- Collier, R., & Collier, J. (2012). Environmental Physiology of Livestock. Environmental Physiology of Livestock.More infoAbstract: Environmental stress is one of the most significant factors affecting livestock performance and health, and it is only expected to increase with effects of global warming. Environmental Physiology of Livestock brings together the latest research on environmental physiology, summarizing progress in the field and providing directions for future research. Recent developments in estimating heat stress loads are discussed, as well as key studies in metabolism, reproduction, and genetic expressions. Environmental Physiology of Livestock begins with a survey of current heat indexing tools, highlighting recent discoveries in animal physiology, changes in productivity levels, and new technologies available to better estimate stress response. Using this synopsis as a point of orientation, later chapters hone in on major effects of heat stress, including changing metabolic pathways and nutrient requirements, endocrine regulation of acclimation to environmental stress, and reduced reproductive performance. The text concludes with a thorough discussion of environmental effects on gene expressions, providing important insight for future breeding practices. © 2012 John Wiley & Sons, Inc.
- Collier, R., Annen-Dawson, E., & Pezeshki, A. (2012). Effects of continous lactation and short dry periods on mammary function and animal health. Animal, 6, 403-414.
- Collier, R., Hernandez, L., & Horseman, N. (2012). Serotonin as a homeostatic regulator of lactation. Domestic Animal Endocrin, 43(2), 161-170.More infoSerotonin (5-HT), a neurotransmitter produced in mammary epithelial cells (MECs), acts via autocrine-paracrine mechanisms on MECs to regulate milk secretion in a variety of species. Recent studies in dairy cows reported that 5-HT ligands affect milk yield and composition. We determined the mRNA expression of bovine 5-HT receptor (5-HTR) subtypes in bovine mammary tissue (BMT) and cultured bovine MECs. We then used pharmacologic agents to evaluate functional activities of 5-HTR subtypes. The mRNAs for five receptor isoforms (5-HTR1B, 5-HTR2A, 5-HTR2B, 5-HTR4, and 5-HTR7) were identified by conventional reverse transcription PCR, real-time PCR, and in situ hybridization in BMT. In addition to luminal MEC expression, 5-HTR4 was expressed in myoepithelium, and 5-HTR1B, HTR2A, and HTR2B were expressed in small mammary blood vessels. Studies to date report that there are multiple 5-HTR isoforms in mammary tissue of rodents, humans, and cattle. Inhibition of the 5-HT reuptake transporter with selective 5-HT reuptake inhibitors (SSRIs) disrupted tight junctions and decreased milk protein mRNA expression in mouse, human, and bovine mammary cells. Selective 5-HT reuptake inhibitors act to increase the cellular exposure to 5-HT by preventing reuptake of 5-HT by the cell and eventual degradation. Increasing 5-HT concentration in milk via inhibiting its reuptake (SSRI), or by increasing the precursor for 5-HT synthesis 5-hydroxytryptophan, accelerated decline in milk synthesis at dry-off. We conclude that the 5-HT system in mammary tissue acts as a homeostatic regulator of lactation.
- Collier, R., Hernandez, L., & Horseman, N. (2012). Serotonin as a homeostatic regulator of lactation. Domestic Animal Endocrinol, 43, 161-170.More infoSerotonin (5-HT), a neurotransmitter produced in mammary epithelial cells (MECs), acts via autocrine–paracrine mechanisms on MECs to regulate milk secretion in a variety of species. Recent studies in dairy cows reported that 5-HT ligands affect milk yield and composition. We determined the mRNA expression of bovine 5-HT receptor (5-HTR) subtypes in bovine mammary tissue (BMT) and cultured bovine MECs. We then used pharmacologic agents to evaluate functional activities of 5-HTR subtypes. The mRNAs for five receptor isoforms (5-HTR1B, 5-HTR2A, 5-HTR2B, 5-HTR4, and 5-HTR7) were identified by conventional reverse transcription PCR, real-time PCR, and in situ hybridization in BMT. In addition to luminal MEC expression, 5-HTR4 was expressed in myoepithelium, and 5-HTR1B, HTR2A, and HTR2B were expressed in small mammary blood vessels. Studies to date report that there are multiple 5-HTR isoforms in mammary tissue of rodents, humans, and cattle. Inhibition of the 5-HT reuptake transporter with selective 5-HT reuptake inhibitors (SSRIs) disrupted tight junctions and decreased milk protein mRNA expression in mouse, human, and bovine mammary cells. Selective 5-HT reuptake inhibitors act to increase the cellular exposure to 5-HT by preventing reuptake of 5-HT by the cell and eventual degradation. Increasing 5-HT concentration in milk via inhibiting its reuptake (SSRI), or by increasing the precursor for 5-HT synthesis 5-hydroxytryptophan, accelerated decline in milk synthesis at dry-off. We conclude that the 5-HT system in mammary tissue acts as a homeostatic regulator of lactation.
- Deaver, S., Hoyer, P., Dial, S., Field, M., Collier, R., & Rhoads, M. (2012). Localization of ghrelin and its receptor in the reproductive tract of Holstein heifers. J Dairy Sci, 96, 150-157.
- Elsasser, T. H., Li, C., Shaffer, J., & Collier, R. J. (2012). Effects of Environment on Animal Health: Mechanisms and Regulatory Inputs. Environmental Physiology of Livestock, 129-164.
- Hall, L. W., Garcia, S., & Collier, R. J. (2012). Climatology: The effects of heat stress on beef cattle production. Climatology: New Developments, 43-62.More infoAbstract: Heat stress in cattle occurs when the heat load associated with ambient air temperature solar radiation and humidity exceeds the ability of the cow to dissipate excess heat from work and metabolism. This results in an elevated core body temperature, above the normal physiological range. The primary environmental factors causing the stress are temperature and humidity (measured by the THI index), solar radiation, and wind speed. Heat stress results in disruption of homeostasis, elevated basal metabolism and initiation of physiological acclimation responses. Cattle experiencing heat stress have an elevated body temperature, an increased respiration rate, and decreased feed intake. Insulin production increases and adipose tissues are unavailable for catabolic fuel. Many additional physiological pathways are compromised resulting in a loss of production (growth, reproduction, lactation). Reduced production always has an economic impact. The two major beef production entities affected by heat stress are: cow-calf operations, and feedlots. The ability of animals to adapt to the environment is known as acclimatization and is essential to long-term success of cow-calf operations. In contrast, feedlot populations have a constant turnover in cattle that are often shipped from various climates and sudden changes in environmental conditions can lead to high rates of death loss as animals are unable to quickly alter their metabolism to acclimate to the stress. The ability to acclimate is influenced by breed of cattle. Traits such as hair type, skin pigment, and ability to sweat can precondition cattle for heat resistance. Both short and long term management can reduce the magnitude of climate related stress. In feedlots, fat steers get preferential treatment and location. This group is the most susceptible to heat stress and should receive top priority in hot and humid scenarios. Nutrition is also a tool to reduce the heat load caused by metabolism (heat of fermentation). Feedlots have no natural covering for the ground or shade for the animals that many cow-calf operations benefit from. In beef cattle production, market economics are the driving force for determining degree of environmental protection. Heat stress can decrease milk production in cows resulting in lower 205 day weaning weights, and decrease feed intake and efficiency in a feedlot. Any loss in performance results in a reduced profit. This loss in value provides an estimate of the size of capital expenditure that can be justified to be put towards improvements in facilities to reduce heat stress in future beef cattle production. © 2012 Nova Science Publishers, Inc. All Rights Reserved.
- Long, N. M., Collier, R. J., & Smith, J. F. (2012). Short communication: Comparison of 2 methods of assessing calf birth weights in dairy calves. Journal of Dairy Science, 95(12), 7206-7209.More infoPMID: 23063164;Abstract: The collection of calf birth weight on US dairies is not a common practice. Calf birth weight was collected on 3 dairies (2 Holstein herds and 1 Jersey herd) over a 6-wk period. All calf birth weights were collected less than 2h after birth. A total of 872 calves were weighed by a spring scale and their weight was also estimated using a hoof circumference tape, with both weights and sex recorded. The general linear models procedure (PROC GLM; SAS Institute Inc., Cary, NC) was used to estimate least squares means for spring scale birth weight along with sex of the calf and dairy. Calf spring scale versus hoof circumference-estimated birth weight was compared using the regression procedure (PROC REG; SAS Institute Inc.). Calf birth weight was also broken down into increments, and spring scale versus hoof circumference-estimated birth weight was compared by t-test. Bull calves had a heavier birth weight compared with heifer calves [36.7±0.4kg (n=450) vs. 34.6±0.4kg (n=422), respectively]. The dairy on which calves were born had a significant effect on calf birth weight [dairy 1: 36.8±0.4kg (n=204); dairy 2: 39.5±0.2kg (n=463); dairy 3: 25.9±0.4kg (n=205)]. When the spring scale calf birth weight was linearly regressed by hoof circumference-estimated birth weight, a significant relationship was observed, with an R2 value of 0.91. For calves weighing less than 31.3kg, the hoof circumference tape overestimated calf birth weight compared with the spring scale. However, for calves that weighed between 31.3 and 44.9kg, no significant difference was observed between spring scale and hoof circumference tape-estimated birth weight. For calves weighing greater than 44.9kg, the hoof circumference tape underestimated birth weight compared with the spring scale. Collection of calf BW by spring scale or estimated by hoof circumference tape appeared to be comparable for most calves because most calves weighed between 31 and 45kg, but caution should be used for calves with a light or heavy birth weight. © 2012 American Dairy Science Association.
- Long, N., Collier, R., & Smith, J. (2012). Comparison of two methods of collecting calf birthweights (BW) in dairy calves. J Dairy Sci, 95, 7206-7209.
- Renaudeau, D., Collin, A., Yahav, S., Basilio, V. D., Gourdine, J. L., & Collier, R. J. (2012). Adaptation to hot climate and strategies to alleviate heat stress in livestock production. Animal, 6(5), 707-728.More infoPMID: 22558920;Abstract: Despite many challenges faced by animal producers, including environmental problems, diseases, economic pressure, and feed availability, it is still predicted that animal production in developing countries will continue to sustain the future growth of the world's meat production. In these areas, livestock performance is generally lower than those obtained in Western Europe and North America. Although many factors can be involved, climatic factors are among the first and crucial limiting factors of the development of animal production in warm regions. In addition, global warming will further accentuate heat stress-related problems. The objective of this paper was to review the effective strategies to alleviate heat stress in the context of tropical livestock production systems. These strategies can be classified into three groups: those increasing feed intake or decreasing metabolic heat production, those enhancing heat-loss capacities, and those involving genetic selection for heat tolerance. Under heat stress, improved production should be possible through modifications of diet composition that either promotes a higher intake or compensates the low feed consumption. In addition, altering feeding management such as a change in feeding time and/or frequency, are efficient tools to avoid excessive heat load and improve survival rate, especially in poultry. Methods to enhance heat exchange between the environment and the animal and those changing the environment to prevent or limit heat stress can be used to improve performance under hot climatic conditions. Although differences in thermal tolerance exist between livestock species (ruminants > monogastrics), there are also large differences between breeds of a species and within each breed. Consequently, the opportunity may exist to improve thermal tolerance of the animals using genetic tools. However, further research is required to quantify the genetic antagonism between adaptation and production traits to evaluate the potential selection response. With the development of molecular biotechnologies, new opportunities are available to characterize gene expression and identify key cellular responses to heat stress. These new tools will enable scientists to improve the accuracy and the efficiency of selection for heat tolerance. Epigenetic regulation of gene expression and thermal imprinting of the genome could also be an efficient method to improve thermal tolerance. Such techniques (e.g. perinatal heat acclimation) are currently being experimented in chicken. © 2012 The Animal Consortium.
- Roy, K. S., & Collier, R. J. (2012). Regulation of Acclimation to Environmental Stress. Environmental Physiology of Livestock, 49-63.
- Collier, R. J., Annen-Dawson, E. L., & Pezeshki, A. (2012). Effects of continous lactation and short dry periods on mammary function and animal health. Animal, 3(6), 403-414.
- Collier, R. J., Hernandez, L. L., Vomachka, A. J., & Horseman, N. D. (2011). Suppression of lactogenic activity by a selective serotonin reuptake inhibitor (SSRI). J. Endo, 209, 45-54.
- Collier, R. J., Reneadeau, D., Collin, A., Yahav, S., de Basillo, V., & Gourdine, J. L. (2012). Adaptation to hot climate and strategies to alleviate heat stress in livestock production. Animal.
- Hadsell, D. L., Olea, W., Wei, J., Fiorotto, M. L., Matsunami, R. K., Engler, D. A., & Collier, R. J. (2011). Developmental regulation of mitochondrial biogenesis and function in the mouse mammary gland during a prolonged lactation cycle. Physiological Genomics, 43(6), 271-285.More infoPMID: 21189371;Abstract: The regulation of mitochondrial biogenesis and function in the lactating mammary cell is poorly understood. The goal of this study was to use proteomics to relate temporal changes in mammary cell mitochondrial function during lactation to changes in the proteins that make up this organelle. The hypothesis tested was that changes in mammary cell mitochondrial biogenesis and function during lactation would be accounted for by coordinated changes in the proteins of the electron transport chain and that some of these proteins might be linked by their expression patterns to PPARGC1α and AMP kinase. The mitochondrial proteome was studied along with markers of mitochondrial biogenesis and function in mammary tissue collected from mice over the course of a single prolonged lactation cycle. Mammary tissue concentrations of AMP and ADP were increased (P < 0.05) during early lactation and then declined with prolonged lactation. Similar changes were also observed for mitochondrial ATP synthesis activity, mitochondrial mass and DNA copy number. Analysis of the mammary cell mitochondrial proteome identified 244 unique proteins. Of these, only two proteins of the electron transport chain were found to increase during early lactation. In contrast, coordinated changes in numerous electron transport chain proteins were observed both during mid- and late lactation. There were six proteins that could be directly linked to PPARGC1α through network analysis. Abundance of PPARGC-1α and phosphorylation of AMP kinase was highest on day 2 postpartum. The results suggest that the increases in mammary mitochondria ATP synthesis activity during early lactation results from changes in only a limited number proteins. In addition, decreases in a handful of proteins linked to lipid oxidation could be temporally linked to decreases in PPARGC1α and phospho-AMP kinase suggesting potential roles for these proteins in coordinating mammary gland metabolism during early lactation. © 2011 by the American Physiological Society.
- Hernandez, L. L., Collier, J. L., Vomachka, A. J., Collier, R. J., & Horseman, N. D. (2011). Suppression of lactation and acceleration of involution in the bovine mammary gland by a selective serotonin reuptake inhibitor. Journal of Endocrinology, 209(1), 45-54.More infoPMID: 21307120;Abstract: Serotonin (5-HT) is a homeostatic regulator of lactation. Selective 5-HT reuptake inhibitors (SSRI) are commonly prescribed pharmaceuticals that inhibit activity of the 5-HT reuptake transporter, increasing cellular exposure to 5-HT. Use of SSRIs has been shown to alter lactation performance in humans and 5-HT has been shown to reduce milk yield in cattle. However, it has not been determined how SSRI treatments affect the bovine mammary gland. We evaluated the effects of SSRI (fluoxetine (FLX)) administration on tight junctions (TJs) and milk protein gene expression in a lactogenic culture model, using primary bovine mammary epithelial cells (pBMEC). Additionally, we evaluated the effects of intramammary infusions of FLX and 5-hydroxytryptophan on milk production and TJ status in multiparous Holstein cows at dry-off. Treatment of pBMEC cultured on permeable membranes disrupted TJs, as measured by transepithelial resistance and immunostaining for zona occludens 1. Correspondingly, treatment of '3D', collagenembedded lactogenic cultures of pBMEC with FLX suppressed milk protein gene expression (α-lactalbumin and β-casein) in a concentration-dependent manner. Finally, intramammary treatment of Holstein cows with FLX resulted in an accelerated rate of milk decline. Additionally, TJ permeability increased in FLX-treated animals, as measured by plasma lactose and milk Na+ and K+ levels. Results of these experiments imply that SSRI administration accelerates the rate of mammary gland involution through disassembly of TJs and inhibition of milk protein gene expression in vitro and in vivo, leading to reduction of milk yield. © 2011 Society for Endocrinology.
- Hernandez, L., Vomachka, A., Collier, R., & Horseman, N. (2011). Suppression of lactogenic activity by a selective serotonin reuptake inhibitor (SSRI). J Endo, 209, 45-54.
- Renadeau, D., Collin, A., Yahav, S., de, B. V., Gourdine, J., & Collier, R. (2011). Adaptation to hot climate and strategies to alleviate heat stress in livestock production. Animal.More infoDOI: 10.1017/S1751731111002448
- Gebremedhin, K. G., Lee, C. N., Hillman, P. E., & Collier, R. J. (2010). Physiological responses of dairy cows during extended solar exposure. American Society of Agricultural and Biological Engineers Annual International Meeting 2010, 6, 5028-5042.More infoAbstract: Sweating and respiration rates, and skin (dorsal) and core (rectal) temperatures of 12 Holstein dairy cows were measured in controlled environments at the William Parker Agricultural Research Complex, University of Arizona-Tucson. The focus of the study was: (1) to establish the pattern (linear or periodic) of sweating, (2) to establish whether skin or core temperature drives sweating, (3) to determine how cows react to a prolonged solar exposure, and (4) to compare dairy cows physiological responses to hot and humid versus hot and dry environmental conditions. The cows were divided into two groups of 6 cows each and were housed alternately between two chambers. The two chambers were identical but one (experimental chamber) included solar lamps to simulate solar load. The cows were alternately exposed to 550 W/m2 solar load, THI was initially set at 83 and later at 79.6, and air velocity in the measurement area on the dorsal surface was between 0.8 and 1.2 m/s. Skin temperature was greater than 35°C (threshold for heat stress). There was considerable variation in sweating rates between cows of the Holstein breed. Cows sweat in a cyclic manner and the results suggest that skin temperature is the primary driving force for sweating. The maximum sweating rate of dairy cows and feedlot heifers is around 660 g/m2-h. A prolonged exposure to hot and dry environmental condition made entirely black or predominantly black cows to foam in the mouth, stick their tongues out, and drool, and immediate intervention with water spraying helped to alleviate the thermal stress.
- Gebremedhin, K. G., Lee, C. N., Hillman, P. E., & Collier, R. J. (2010). Physiological responses of dairy cows during extended solar exposure. Transactions of the ASABE, 53(1), 239-247.More infoAbstract: Sweating and respiration rates, and skin (dorsal) and core (rectal) temperatures of 12 Holstein dairy cows were measured in controlled environments at the William Parker Agricultural Research Complex, University of Arizona-Tucson. The focus of the study was: (1) to establish the pattern (linear or periodic) of sweating, (2) to establish whether skin or core temperature drives sweating, (3) to determine how cows respond to a prolonged solar exposure, and (4) to compare dairy cows physiological responses to hot and humid versus hot and dry environmental conditions. The 12 cows were divided into two groups of six cows each and were housed alternately between two chambers. The two chambers were identical, but one (experimental chamber) included solar lamps to simulate solar load. The cows were alternately exposed to 550 W/m 2 solar load, THI at 79.6, and air velocity in the measurement area (dorsal surface) was maintained at 1.0 m/s. Skin temperature was greater than 35° C (threshold for heat stress). There was considerable variation in sweating rates between cows. Cows sweat in a cyclic manner, and the results suggest that skin temperature is the primary driving force for sweating. The maximum sweating rate of dairy cows was around 660 g/m 2-h. © 2010 American Society of Agricultural and Biological Engineers.
- Pezeshki, A., Capuco, A. V., Spiegeleer, B. D., Peelman, L., Stevens, M., Collier, R. J., & Burvenich, C. (2010). An integrated view on how the management of the dry period length of lactating cows could affect mammary biology and defence. Journal of Animal Physiology and Animal Nutrition, 94(5), e7-e30.More infoPMID: 20546070;Abstract: The dry period is necessary to facilitate cell turnover in the bovine mammary gland and to optimize milk production in the next lactation. An 8-week dry period has long been the golden standard of management for dairy cows. Genetic improvements and new management technologies have led to higher milk production and a need for re-evaluation of the dry period length. Over the last decade, dry period length has been proposed to be shortened or eliminated mainly from an economic point of view. However, the influence of modified dry period length on the immune defence of the bovine mammary gland and the occurrence of new intramammary infections has not yet been appreciated. The objective of this review is to discuss the bovine mammary gland biology, defence and systemic health when the dry period length is modified. Shortening or eliminating the dry period may minimize or remove the impact of milk accumulation at dry off, thereby lessening the immunodeficiency of the dam that is characteristic of this period. Composition of mammary secretions may change and the extent of tissue remodelling may be reduced when the dry period is reduced or eliminated. Additionally, impact of the dry period length on energy and nutritional status, and on hormonal and local regulatory factors, lead us to hypothesize that changing the dry period length might also affect the response to intramammary infection. It is concluded that there is a need to integrate mammary gland biology and defence mechanisms in studies dealing with modified dry period lengths. © 2010 Blackwell Verlag GmbH.
- Rhoads, M. L., Kim, J. W., Collier, R. J., Crooker, B. A., Boisclair, Y. R., Baumgard, L. H., & Rhoads, R. P. (2010). Effects of heat stress and nutrition on lactating Holstein cows: II. Aspects of hepatic growth hormone responsiveness. Journal of Dairy Science, 93(1), 170-179.More infoPMID: 20059916;Abstract: Heat stress (HS) is a multibillion-dollar problem for the global dairy industry, and reduced milk yield is the primary contributor to this annual economic loss. Feed intake declines precipitously during HS but accounts for only about 35% of the decreased milk synthesis, indicating that the physiological mechanisms responsible for decreased milk production during HS are only partly understood. Thus, our experimental objectives were to characterize the direct effects of HS on the somatotropic axis, a primary regulator of metabolism and milk yield. We recently reported no differences in mean growth hormone (GH) concentrations, GH pulsatility characteristics, or GH response to growth hormone releasing factor in HS versus pair-fed (PF) thermoneutral controls. Despite similarities in circulating GH characteristics, plasma insulin-like growth factor (IGF)-I concentrations were reduced during heat stress conditions but not in PF animals, suggesting that uncoupling of the hepatic GH-IGF axis may occur during HS. We investigated this possibility by measuring proximal indicators of hepatic GH signaling following a GH bolus. Heat stress but not PF decreased abundance of the GH receptor and GH-dependent signal transducer and activator of transcription (STAT)-5 phosphorylation. Consistent with reduced GH signaling through STAT-5, basal hepatic IGF-I mRNA abundance was lower in HS cows. Thus, the reduced hepatic GH responsiveness (in terms of IGF-I gene expression) observed during HS appears to involve mechanisms at least partially independent of reduced nutrient intake. The physiological significance of reduced hepatic GH receptor abundance during HS is unclear at this time. Aside from reducing IGF-I production, it may reduce other GH-sensitive bioenergetic processes such as gluconeogenesis. © 2010 American Dairy Science Association.
- Zimbelman, R. B., Baumgard, L. H., & Collier, R. J. (2010). Effects of encapsulated niacin on evaporative heat loss and body temperature in moderately heat-stressed lactating Holstein cows. Journal of Dairy Science, 93(6), 2387-2394.More infoPMID: 20494147;Abstract: Twelve multiparous Holstein cows (145±9 d in milk) were randomly assigned to receive either 0g/d of encapsulated niacin (control diet; C) or 12g/d of encapsulated niacin (NI) and were exposed to thermoneutral (TN; 7 d) or heat stress (HS; 7 d) conditions in climate-controlled chambers. The temperature-humidity index during TN conditions never exceeded 72, whereas HS conditions consisted of a circadian temperature range in which the temperature-humidity index exceeded 72 for 12h/d. Measures of thermal status obtained 4 times/d included respiration rate (RR); rectal temperature; surface temperature of both shaved and unshaved areas at the rump, shoulder, and tail head; vaginal temperature; and evaporative heat loss (EVHL) of the shoulder shaved and unshaved areas. Cows fed NI had increased free plasma niacin concentrations in both the TN and HS periods (1.70 vs. 1.47±0.17μg/mL). Milk yield did not differ between dietary groups or periods. Dry matter intake was not affected by NI, but decreased (3%) for both C and NI treatments during HS. Water intake was increased during HS in both treatments (C: 40.4 vs. 57.7±0.8L/d for TN and HS, respectively; NI: 52.7 vs. 57.7±0.8L/d for TN and HS, respectively). Average EVHL for shaved and unshaved skin for C and NI treatments was higher during HS (90.1 vs. 108.1g/m2 per hour) than TN (20.7 vs. 15.7±4.9g/m2 per hour). Between 1000 and 1600h, mean EVHL for shaved and unshaved areas for NI fed cows was higher than for C fed cows (106.9 vs. 94.4±4.9g/m2 per hour). The NI fed cows had decreased rectal temperatures during HS compared with the C fed cows (38.17 vs. 38.34±0.07°C) and had lower vaginal temperatures (38.0 vs. 38.4±0.02°C). Calculated metabolic rate decreased during HS regardless of diet (50.25 and 49.70±0.48 kcal/kg of body weight per day for TN and HS, respectively). Feeding NI increased free plasma NI levels, increased EVHL during peak thermal load, and was associated with a small but detectable reduction in rectal and vaginal temperatures in lactating dairy cows experiencing a mild thermal load. © 2010 American Dairy Science Association.
- Collier, R., Hernandez, L. L., Limesand, S. W., Collier, J. L., Horseman, N. D., & Collier, R. J. (2009). The bovine mammary gland expresses multiple functional isoforms of serotonin receptors. The Journal of endocrinology, 203(1).More infoRecent studies in dairy cows have demonstrated that serotonergic ligands affect milk yield and composition. Correspondingly, serotonin (5-HT) has been demonstrated to be an important local regulator of lactational homeostasis and involution in mouse and human mammary cells. We determined the mRNA expression of bovine 5-HT receptor (HTR) subtypes in bovine mammary tissue (BMT) and used pharmacological agents to evaluate functional activities of 5-HT receptors. The mRNAs for five receptor isoforms (HTR1B, 2A, 2B, 4, and 7) were identified by conventional real-time (RT)-PCR, RT quantitative PCR, and in situ hybridization in BMT. In addition to luminal mammary epithelial cell expression, HTR4 was expressed in myoepithelium, and HTR1B, 2A, and 2B were expressed in small mammary blood vessels. Serotonin suppressed milk protein mRNA expression (alpha-lactalbumin and beta-casein mRNA) in lactogen-treated primary bovine mammary epithelial cell (BMEC) cultures. To probe the functional activities of individual receptors, caspase-3 activity and expression of alpha-lactalbumin and beta-casein were measured. Both SB22489 (1B antagonist) and ritanserin (2A antagonist) increased caspase-3 activity. Expression of alpha-lactalbumin and beta-casein mRNA levels in BMEC were stimulated by low concentrations of SB224289, ritanserin, or pimozide. These results demonstrate that there are multiple 5-HT receptor isoforms in the bovine mammary gland, and point to profound differences between serotonergic systems of the bovine mammary gland and the human and mouse mammary glands. Whereas human and mouse mammary epithelial cells express predominately the protein for the 5-HT(7) receptor, cow mammary epithelium expresses multiple receptors that have overlapping, but not identical, functional activities.
- Correa-Calderón, A., Santos, G. d., Avendaño, L., Rivera, F., Alvarez, D., Ardon, F., Diaz, R., & Collier, R. (2009). Cooling and conception rate in Holstein heifers with heat stress. Archivos de Zootecnia, 58(222), 231-239.More infoAbstract: The objective of this study was to evaluate the effect of a timed artificial insemination protocol plus a period of artificial cooling on conception rate and physiologic response of heifers under heat stress. Ninety Holstein heifers were randomly allotted into one of three treatments: A control treatment (T1) with visual heat detection and insemination morning-evening (n=30), a second treatment (T2) under a timed artificial insemination protocol and a third treatment (T3) with the same protocol than T2 plus an artificial cooling period beginning 11 d before and ending 21 d after insemination. The experiment was divided in two periods: the first period was from June 25 to July 26, and the second one from August 15 to September 16. In period 1, heifers in T3 had a lower (p
- Hadsell, D. L., George, J., Abraham, P. A., Collier, R. J., & Lambert, B. D. (2009). Technical note: Assessing the functional capacity of mitochondria isolated from lactating mammary tissue: Choose your chelating agent wisely. Journal of Dairy Science, 92(5), 2038-2045.More infoPMID: 19389961;Abstract: Previous work has indicated that respiratory activity of mitochondrial preparations prepared from lactating mammary tissue is often much lower than that of mitochondria isolated from other organs such as the liver. Initial studies in our own laboratory also found that mammary mitochondria prepared from lactating mice had much lower ATP synthesis activity than those isolated from liver tissue obtained from the same animals. In this paper, we describe an improved procedure for obtaining coupled mitochondria from the mammary tissue of lactating mice. Using a high-throughput assay for mitochondrial ATP synthesis, we demonstrated that mammary mitochondria, unlike liver mitochondria, are sensitive to the concentration of bovine serum albumin and to the choice of chelating agent used in the preparation and assay buffers. Mammary mitochondria prepared and assayed in buffers containing 1 mM ethylene glycol-bis-(β-aminoethyl ether)-N,N' tetraacetic acid (EGTA) and 0.4% bovine serum albumin have a similar ATP synthesis activity as liver mitochondria. In addition, we show that the chelating agent EDTA ablates the ATP synthesis capacity of mammary mitochondria through a mechanism that does not involve the release of cytochrome c. We also demonstrate that these improved isolation and assay procedures are both scalable and applicable to bovine mammary tissue, and we describe optimal conditions for cryopreservation and recovery of functionally active mitochondria. This work will facilitate future studies aimed at determining the importance of mammary mitochondria to milk production. © American Dairy Science Association, 2009.
- Hernandez, L. L., Limesand, S. W., Collier, J. L., Horseman, N. D., & Collier, R. J. (2009). The bovine mammary gland expresses multiple functional isoforms of serotonin receptors. Journal of Endocrinology, 203(1), 123-131.More infoPMID: 19654143;PMCID: PMC2741409;Abstract: Recent studies in dairy cows have demonstrated that serotonergic ligands affect milk yield and composition. Correspondingly, serotonin (5-HT) has been demonstrated to be an important local regulator of lactational homeostasis and involution in mouse and human mammary cells. We determined the mRNA expression of bovine 5-HT receptor (HTR) subtypes in bovine mammary tissue (BMT) and used pharmacological agents to evaluate functional activities of 5-HT receptors. The mRNAs for five receptor isoforms (HTR1B, 2A, 2B, 4, and 7) were identified by conventional real-time (RT)-PCR, RT quantitative PCR, and in situ hybridization in BMT. In addition to luminal mammary epithelial cell expression, HTR4 was expressed in myoepithelium, and HTR1B, 2A, and 2B were expressed in small mammary blood vessels. Serotonin suppressed milk protein mRNA expression (α-lactalbumin and β-casein mRNA) in lactogen-treated primary bovine mammary epithelial cell (BMEC) cultures. To probe the functional activities of individual receptors, caspase-3 activity and expression of α-lactalbumin and β-casein were measured. Both SB22489 (1B antagonist) and ritanserin (2A antagonist) increased caspase-3 activity. Expression of α-lactalbumin and β-casein mRNA levels in BMEC were stimulated by low concentrations of SB224289, ritanserin, or pimozide. These results demonstrate that there are multiple 5-HT receptor isoforms in the bovine mammary gland, and point to profound differences between serotonergic systems of the bovine mammary gland and the human and mouse mammary glands. Whereas human and mouse mammary epithelial cells express predominately the protein for the 5-HT7 receptor, cow mammary epithelium expresses multiple receptors that have overlapping, but not identical, functional activities. © 2009 Society for Endocrinology.
- Rhoads, M. L., Rhoads, R. P., VanBaale, M. J., Collier, R. J., Sanders, S. R., Weber, W. J., Crooker, B. A., & Baumgard, L. H. (2009). Effects of heat stress and plane of nutrition on lactating Holstein cows: I. Production, metabolism, and aspects of circulating somatotropin. Journal of Dairy Science, 92(5), 1986-1997.More infoPMID: 19389956;Abstract: Heat stress is detrimental to dairy production and affects numerous variables including feed intake and milk production. It is unclear, however, whether decreased milk yield is primarily due to the associated reduction in feed intake or the cumulative effects of heat stress on feed intake, metabolism, and physiology of dairy cattle. To distinguish between direct (not mediated by feed intake) and indirect (mediated by feed intake) effects of heat stress on physiological and metabolic indices, Holstein cows (n = 6) housed in thermal neutral conditions were pair-fed (PF) to match the nutrient intake of heat-stressed cows (HS; n = 6). All cows were subjected to 2 experimental periods: 1) thermal neutral and ad libitum intake for 9 d (P1) and 2) HS or PF for 9 d (P2). Heat-stress conditions were cyclical with daily temperatures ranging from 29.7 to 39.2°C. During P1 and P2 all cows received i.v. challenges of epinephrine (d 6 of each period), and growth hormone releasing factor (GRF; d 7 of each period), and had circulating somatotropin (ST) profiles characterized (every 15 min for 6 h on d 8 of each period). During P2, HS cows were hyperthermic for the entire day and peak differences in rectal temperatures and respiration rates occurred in the afternoon (38.7 to 40.2°C and 46 to 82 breaths/min, respectively). Heat stress decreased dry matter intake by greater than 35% and, by design, PF cows had similar reduced intakes. Heat stress and PF decreased milk yield, although the pattern and magnitude (40 and 21%, respectively) differed between treatments. The reduction in dry matter intake caused by HS accounted for only approximately 35% of the decrease in milk production. Both HS and PF cows entered into negative energy balance, but only PF cows had increased (approximately 120%) basal nonesterified fatty acid (NEFA) concentrations. Both PF and HS cows had decreased (7%) plasma glucose levels. The NEFA response to epinephrine did not differ between treatments but was increased (greater than 50%) in all cows during P2. During P2, HS (but not PF) cows had a modest reduction (16%) in plasma insulin-like growth factor-I. Neither treatment nor period had an effect on the ST response to GRF and there was little or no treatment effect on mean ST levels or pulsatility characteristics, but both HS and PF cows had reduced mean ST concentrations during P2. In summary, reduced nutrient intake accounted for just 35% of the HS-induced decrease in milk yield, and modest changes in the somatotropic axis may have contributed to a portion of the remainder. Differences in basal NEFA between PF and HS cows suggest a shift in postabsorptive metabolism and nutrient partitioning that may explain the additional reduction in milk yield in cows experiencing a thermal load. © American Dairy Science Association, 2009.
- Shuhai, L. i., Gebremedhin, K. G., Lee, C. N., & Collier, R. J. (2009). Evaluation of thermal stress indices for cattle. American Society of Agricultural and Biological Engineers Annual International Meeting 2009, 4, 2283-2302.More infoAbstract: Thermal environment is an important factor that affects the growth and development of domestic animals. Incorporating various environmental factors into an index greatly facilitates assessing and managing the environment for livestock. Thermal stress is reflected by the physiological responses exhibited by animals including skin temperature, core (rectal) temperature, sweating and respiration rates. In this study, the measurement data that consist of the physiological responses (skin temperature, rectal temperature, sweating rate and respiration rate) of cattle and environmental conditions (air temperature, relative humidity, solar radiation and air velocity)measured at four different sites cross US with different breeds of cows and heifers. The data were used to examine the probability distributions of the physiological responses-skin temperature, sweating rate and respiration rate of cows under stress conditions. Skin temperature and respiration rate were found to follow normal distribution and sweating rate follow Weibull distribution. The effectiveness of eight environmental indices (THI: temperature humidity index; THIadj: adjusted temperature humidity index; TBG: temperature of black globe; BGHI: black-globe humidity index; ETI: equivalent temperature index; ESI: environmental stress index; HLI: heat load index; RRP: respiratory rate predictor) were evaluated based on their correlation coefficients with the physiological responses. Skin temperature is the physiological response that responded to environment conditions sensitively. Among the eight thermal indices examined, THIadj, BGHI and RRP were those most correlated with skin temperature.
- Annen, E. L., Stiening, C. M., Crooker, B. A., Fitzgerald, A. C., & Collier, R. J. (2008). Effect of continuous milking and prostaglandin E2 on milk production and mammary epithelial cell turnover, ultrastructure, and gene expression. Journal of Animal Science, 86(5), 1132-1144.More infoPMID: 18272860;Abstract: Mammary epithelial cell (MEC) growth is reduced in continuously milked (CM) mammary glands, and administration of a mammogenic compound such as prostaglandin E2 (PGE2) at parturition might improve MEC growth in CM tissue. The objectives were to 1) compare MEC turnover, ultrastructure, and gene expression in CM and involuting mammary tissue, and 2) evaluate the effects of CM and intramammary infusion of PGE2 on early lactation MEC turnover, ultrastructure, mammary gene expression, milk yield, and composition. First- and second-lactation cows (n = 8) were used in a half-udder model, in which one-half was dry for 60 d (CTL) and the other was CM. Udder halves (n = 16) were assigned to a postpartum (PP) treatment of PGE 2 (+PGE2; 875 μg/10 mL of medium-chain triglyceride oil) or no PGE2 (-PGE2) treatment at parturition and at 72 h PP. Biopsies of CM and CTL quarters were obtained during milk stasis (MS) of the CTL half at 3 and 7 d after dry-off of the CTL half (3d-MS; 7d-MS) and postpartum (PP) at 2 and 4 d (2d-PP; 4d-PP). Milk yield was reduced (P < 0.01) in CM udder halves compared with CTL halves (13.2 vs. 22.1 kg/d), but reductions were less in second-lactation cows. The apoptotic index was greater (P < 0.05) in CTL glands than in CM glands (3d-MS, 0.52 vs. 0.11% and 7d-MS, 0.24 vs. 0.12, respectively). Proliferation of MEC was unchanged at Sd-MS, but was increased (P - 0.01) in CTL halves at 7d-MS compared with CM halves (3.10 vs. 0.93%). At 2d-PP, MEC proliferation was increased (P = 0.05) in CM halves compared with CTL halves (1.3 vs. 0.6%), but was unaffected by PGE2 (P > 0.2). Apoptosis was elevated in early lactation regardless of treatment. Ultrastructure was unchanged by dry period length or PGE2. In prepartum tissue, involution in CTL halves increased (P < 0.05) the expression of the proapoptotic genes Bcl-2-associated x protein (bax) and IGFBP5 and decreased (P < 0.05) a-lactalbumin expression compared with CM tissue. In PP mammary tissue, CTL halves expressed greater (P < 0.05) levels of ATP-binding cassette 1 (ABC1) and IGFBP5. Treatment with PGE2 did not alter (P > 0.1) gene expression. The results confirm that CM reduced milk yield of cows with a mammary growth requirement. Reduced MEC turnover and milk yield were not alleviated by IMI of PGE2, which indicates that peripartum PGE2 concentrations in CM glands are not limiting mammary growth or milk synthesis. ©2008 American Society of Animal Science. All rights reserved.
- Collier, R. J., Bilby, T. R., Rhoads, M. E., Baumgard, L. H., & Rhoads, R. P. (2008). Effects of climate change on dairy cattle production. Annals of Arid Zone, 47(3-4), 393-411.More infoAbstract: There are three dominant gene groups in the dairy cattle population [Bos taurus, Bos indicus and Sanga (hybrid of first two)] with varying levels of resistance to thermal stress. Bos taurus cattle have a greater sensitivity to elevated environmental conditions and superior resistance to cold stress than either Bos indicus or Sanga, due to increased levels of endogenous heat production associated with increased milk production and feed intake. However, there are also molecular and phenotypic differences in hair coat characteristics and cellular responses to thermal stress as well. Climate change associated with greenhouse warming will have the greatest impact on Bos indicus cattle populations, but will also adversely affect all breeds to some degree. New data suggests that the upper Temperature Humidity Index (THI) threshold for high-producing (>35 kg d-1) Bos taurus cattle should be a THI daily minimum of 65 and average THI of 68. There is also strong evidence that the upper threshold THI for reproduction is lower than that for lactation. However, several new management technologies are now available to help reduce the negative impact of thermal stress on cattle reproduction. Additionally, only half of the loss in milk yield to thermal stress can be accounted for by a decrease in feed intake with the remainder likely associated with altered carbohydrate and fat metabolism and/or direct effects on milk synthesis and secretion. This suggests that nutritional management strategies may provide opportunities to improve lactation performance of dairy cattle during periods of thermal stress.
- Collier, R. J., Collier, J. L., Rhoads, R. P., & Baumgard, L. H. (2008). Invited review: Genes involved in the bovine heat stress response. Journal of Dairy Science, 91(2), 445-454.More infoPMID: 18218730;Abstract: The cellular heat stress (HS) response is one component of the acute systemic response to HS. Gene networks within and across cells and tissues respond to environmental heat loads above the thermoneutral zone with both intra- and extracellular signals that coordinate cellular and whole-animal metabolism. Activation of these systems appears to be initiated at skin surface temperatures exceeding 35°C as animals begin to store heat and rapidly increase evaporative heat loss (EVHL) mechanisms. Gene expression changes include 1) activation of heat shock transcription factor 1 (HSF1); 2) increased expression of heat shock proteins (HSP) and decreased expression and synthesis of other proteins; 3) increased glucose and amino acid oxidation and reduced fatty acid metabolism; 4) endocrine system activation of the stress response; and 5) immune system activation via extracellular secretion of HSP. If the stress persists, these gene expression changes lead to an altered physiological state referred to as "acclimation," a process largely controlled by the endocrine system. In the acclimated state, metabolism is adjusted to minimize detrimental effects of increased thermal heat load. The role of secreted HSP in feedback regulation of the immune and endocrine system has not yet been investigated. The variation in EVHL among animals and the central role that HSF1 has in coordinating thermal tolerance suggest that there is opportunity to improve thermal tolerance via gene manipulation. Determining the basis for altered energy metabolism during thermal stress will lead to opportunities for improved animal performance via altered nutritional management. © American Dairy Science Association, 2008.
- Collier, R. J., Limesand, S. W., Rhoads, M. L., Rhoads, R. P., & Baumgard, L. H. (2008). Homeorhesis during heat stress. Resource Allocation Theory Applied to Farm Animal Production, 72-88.
- Collier, R. J., Miller, M. A., McLaughlin, C. L., Johnson, H. D., & Baile, C. A. (2008). Effects of recombinant bovine somatotropin (rbST) and season on plasma and milk insulin-like growth factors I (IGF-I) and II (IGF-II) in lactating dairy cows. Domestic Animal Endocrinology, 35(1), 16-23.More infoPMID: 18325721;Abstract: During two studies, effects of recombinant bovine somatotropin (rbST) on plasma and milk IGF's in cows adapted to summer (S; 12 cows) or winter (W; 12 cows) conditions were evaluated. Each study consisted of on-farm periods (30 days) followed by climatology chamber periods (CC; 30 days). Cows were given daily injections of rbST, Sometribove, USAN (25 mg/day; 6 cows each study) or saline (control; 6 cows each study). During on-farm periods, blood and milk (am and pm) samples were collected once weekly. During CC periods, blood samples were collected every 2 days and milk samples (am and pm) were collected daily. Plasma IGF-I and IGF-II were increased in cows treated with rbST. A pronounced seasonal pattern in basal and rbST-stimulated plasma IGF-I but not IGF-II was detected. Higher basal and rbST-stimulated plasma IGF-I concentrations in S occurred despite large decreases in feed intake and energy balance. Milk IGF-I and IGF-II was not affected by rbST treatment or season. Although milk IGF-I and IGF-II concentrations were unaffected by rbST treatment, total IGF-output increased due to increased milk yield. The observed seasonal patterns in plasma IGF-I may be indicative of seasonal differences in the coupling of the somatotropin-IGF axis. In particular, we failed to detect an uncoupling of the somatotropin-IGF-I axis in S despite an induced negative energy balance during thermal stress. © 2008 Elsevier Inc. All rights reserved.
- Gebremedhin, K. G., Hillman, P. E., Lee, C. N., Collier, R. J., Willard, S. T., Arthington, J. D., & Brown-Brandl, T. M. (2008). Sweating rates of dairy cows and beef heifers in hot conditions. Transactions of the ASABE, 51(6), 2167-2178.More infoAbstract: Sweating rates from heat-stressed dairy cows and beef heifers were measured using a "Portable Calorimeter" and a "Bovine Evaporation Meter" designed and fabricated for the studies reported herein. Measurements were taken when cows were in their natural habitat. The focus of the study was to compare sweating rates measured from different breeds of dairy cows and beef heifers, and determine the level of influence of environmental factors (air temperature, relative humidity, solar load, and air velocity) and hair-coat color on sweating rate. The cows were exposed to solar radiation greater than 500 W/m 2 (average 833 ± 132 W/m 2), average THI was 82.7 ± 1.64 for all studies except for the Nebraska data where the THI was 77.4 ± 4. Air velocity in the sample area was between 0.8 and 1.2 m/s, and body (rectal) temperature was greater than 38.8°C (threshold for heat stress). Sweating rates ranged between 189 ± 84.6 and 522 ± 127.7 g/m 2-h. Body temperature ranged between 39.3 ± 0.53°C and 41.7 ± 0.19°C. Differences in sweating rates were statistically significant at P < 0.05 between breeds, between black and white hair coats, and changes in solar load, relative humidity, and air velocity. Wetting the skin surface and increasing air velocity profoundly increased evaporation rate by converting sensible heat to latent heat.
- Gebremedhin, K. G., Hillman, P. E., Lee, C. N., Collier, R. J., Willard, S. T., Arthington, J., & Brown-Brandl, T. (2008). Sweating rates of dairy and feedlot cows under stressful thermal environments. Livestock Environment VIII - Proceedings of the 8th International Symposium, 745-754.More infoAbstract: Sweating rates from heat-stressed dairy and feedlot cows were measured using a Portable Calorimeter and a Bovine Evaporation Meter. Measurements were taken when cows were in their natural habitat. The focus of the study was to compare sweating rates measured from different breeds of dairy and feedlot cows, and determine the level of influence of environmental factors (air temperature, relative humidity, solar load, air velocity), and hair-coat color on sweating rate. The cows were exposed to solar radiation greater than 500 W/m2 (average 833 ± 132 W/m2), average THI was 82.7 ± 1.64 for all studies except for the Nebraska data where the THI was 77.4 ± 4. Air velocity in the sample area was between 0.8 and 1.2 m/s, and body (rectal) temperature was greater than 38.8°C (threshold for heat stress). The range of sweating rates was between 189 ± 84.6 and 522 ± 127.7 g/m 2-h, and that of body temperature was between 39.3 ± 0.53 and 41.7 ± 0.19 °C. Breed difference, hair-coat color. Solar load, and air velocity are critical (statistically significant atP-values
- Hernandez, L. L., Stiening, C. M., Wheelock, J. B., Baumgard, L. H., Parkhurst, A. M., & Collier, R. J. (2008). Evaluation of serotonin as a feedback inhibitor of lactation in the bovine. Journal of Dairy Science, 91(5), 1834-1844.More infoPMID: 18420614;Abstract: Serotonin (5-HT), a neurotransmitter synthesized from tryptophan, has been proposed as a feedback inhibitor of lactation. We determined that the gene coding for tryptophan hydroxylase 1, the rate-limiting enzyme for 5-HT synthesis, is expressed in bovine mammary epithelial cells in vitro and is upregulated by prolactin. In addition, 5-HT reduced the expression of a-lactalbu-min and casein genes in vitro. Furthermore, inhibiting 5-HT synthesis withp-chlorophenylalanine or blocking the 5-HT receptor with methysergide (METH) increased milk protein gene expression. We then evaluated effects of intramammary 5-HT or METH infusion on production and milk composition in 6 multiparous Holstein cows. Cows were assigned to a repeated measures design of contralateral intramammary infusions of METH (20 mg/quarter per d) or saline for 3 d followed by a 7-d washout period before administering 5-HT (50 mg/quarter/d) or SAL for 3 d. For each udder half, milk yield was recorded twice and composition was determined once per day. Blood samples were harvested each day for plasma to determine glucose and nonesterified fatty acid concentrations. Evaporative heat loss, respiration rate, left and right udder temperatures, and rectal temperatures were obtained after each milking to evaluate possible systemic effects of infusions. During METH and saline infusions milk yield increased 10.9%. During 5-HT and saline infusion milk yield decreased 11.1%. Milk yield and physiological responses suggested intramammary 5-HT and METH doses were high enough to cause systemic effects. Infusing saline, METH, and 5-HT increased milk SCC. Infusing 5-HT tended to reduce mean lactose concentration (4.3 vs. 4.6%) relative to saline. Milk protein content was decreased by METH and SAL (2.0%) and was increased (5.8%) by 5-HT followed by a 33% decrease postinfusion. Infusion of METH increased evaporative heat loss 11%, © American Dairy Science Association, 2008.
- Pezeshki, A., Mehrzad, J., Ghorbani, G. R., Spiegeleer, B. D., Collier, R. J., & Burvenich, C. (2008). The effect of dry period length reduction to 28 days on the performance of multiparous dairy cows in the subsequent lactation. Canadian Journal of Animal Science, 88(3), 449-456.More infoAbstract: In a controlled study, the effects of shortened and conventional dry periods (28.2±4.6 vs. 48.8±4 d) on performance of multiparous cow were evaluated. Seventy multiparous Holstein cows were randomly assigned to either a 28- or a 49-d dry period length (DPL). Nine cows were removed from the study and 61 cows were used in the statistical analysis. Cows in the 28-d DPL group were moved to close-up pen and fed only close-up ration during the dry period, whereas those in the 49-d DPL group were given a far-off diet after dry-off until 28 d before expected calving, and then fed the same diet as the cows in the 28-d DPL group. Daily milk yield production was significantly reduced in the 28-d DPL group compared with the 49-d DPL group through 210d in milk (DIM). Neither milk protein nor milk fat was changed in experimental groups. However, fat yield tended to be greater in the 49 d DPL compared with the 28 d DPL. Cows with 28 d DPL lost less body condition in peripartum and gained more body condition score (BCS) by 150DIM. No differences were detected in health disorders, reproduction efficiency and birth weights of calves due to shortened dry period. Our data demonstrate that a shortened dry period under employed management practices is a good management tool in attenuating negative energy balance status without adversely affecting total milk production.
- Stiening, C. M., Hoying, J. B., Abdallah, M. B., Hoying, A. M., Pandey, R., Greer, K., & Collier, R. J. (2008). The effects of endocrine and mechanical stimulation on stage I lactogenesis in bovine mammary epithelial cells. Journal of Dairy Science, 91(3), 1053-1066.More infoPMID: 18292261;Abstract: The study objective was to evaluate the effect of endocrine and mechanical (gel release) signaling on bovine mammary epithelial cell ultrastructure and gene expression. Cultures receiving only one stimulus demonstrated partially differentiated ultrastructure, which included abundant polysomes, limited rough endoplasmic reticulum, and absence of secretory products, whereas the 2 stimuli together induced a more complete lactogenic phenotype that included increased rough endoplasmic reticulum, abundant lipid droplets, and secretory vesicles containing casein micelles. The structural data indicated that although synthesis of milk components was initiated, the copious synthesis and secretion associated with stage II lactogenesis was not evident. Microarray analysis revealed that both prolactin and gel release independently regulated several genes linked to a wide array of cellular activities. In combination, they regulated fewer genes targeted to lactogenesis. Genes regulated by the combination treatment included claudin 7, multiple caseins, xanthine oxidoreductase, and several protein synthesis, packaging, and transport genes. Genes related to structural activity including keratin 15 (morphogenesis), α-spectrin (cell shape via actin cytoskeleton), and chitinase-like protein 1 (tissue remodeling) were up-regulated by the combination treatment as was the transcription factor Kruppel-like factor 2 (KLF-2). However, Snail 2, which down-regulates and inhibits tight junction components, was repressed in response to the combination treatment. These results suggest coordination between endocrine and physical signals at the genomic level that produces a more specific and targeted transcriptional response associated with stage I lactogenesis. A molecular pathway analysis of the differentially expressed genes revealed that genes regulating cell signaling were linked to those regulating cell structure and adhesion. © American Dairy Science Association, 2008.
- Annen, E. L., Fitzgerald, A. C., Gentry, P. C., McGuire, M. A., Capuco, A. V., Baumgard, L. H., & Collier, R. J. (2007). Effect of continuous milking and bovine somatotropin supplementation on mammary epithelial cell turnover. Journal of Dairy Science, 90(1), 165-183.More infoPMID: 17183085;Abstract: Objectives were to determine effects of continuous milking (CM) and bovine somatotropin (bST) administration on 1) mammary epithelial cell (MEC) proliferation, apoptosis, and ultrastructure during late gestation and early lactation, 2) expression of genes associated with proliferation, and apoptosis in mammary epithelial cells, and 3) milk yield and composition. Secondgestation, first dry-period cows were randomly assigned to either continuous bST throughout late gestation and early lactation (+bST; n = 4) or no bST (-bST; n = 4) administration. Within each animal, udder halves were randomly assigned to CM or a 60-d dry period (control) treatment. Daily milk yield and weekly milk composition were measured during the last 60 d of gestation in CM halves and from 1 to 30 d postpartum for both halves. Mammary biopsies were obtained at -20 ± 7, -8 ± 3, +1 ± 0, +7 ± 0, and +20 ± 0 d (mean ± standard error) relative to parturition. Prepartum half-udder milk yield was greater in +bST cows than in -bST cows (9.9 vs. 8.2 kg/d) and postpartum half-udder milk yields were dramatically reduced in CM halves compared with control halves (10.6 vs. 22.2 kg/d), regardless of bST treatment. Proliferation of MEC was reduced in CM halves at -8 d (2.7 vs. 5.4%). Apoptosis of MEC was elevated during early lactation for d +1 and +7 in control halves, but was only increased at d +1 in CM halves. Turnover of MEC was not affected by bST. Ultrastructure data indicated complete involution of the control half and lactation maintenance in CM glands (d -20). By d -8, control tissue contained alveoli in an immature secretory state, but CM tissue contained both lactating and immature alveoli. Postpartum ultrastructure parameters were similar between halves until d 20 when control tissue was composed of a homogeneous population of lactating alveoli, but CM tissue contained lactating, engorged, and resting alveoli. Expression of CCAAT/enhancer binding protein-β (CEBP-β), cyclin D1, and bcl 2 were up-regulated during late gestation, but did not differ between control and CM halves. Expression of α-lactalbumin was increased in CM halves during late gestation, but was not different in CM and control tissue after parturition. Other genes evaluated (bax, insulin-like growth factor binding protein 5, ATPbinding cassette 1, and p27) were not differentially expressed at any timepoints evaluated. Results indicate that CM reduced subsequent half-udder milk yield in primiparous cows through altered MEC turnover and secretory capacity. Negative effects of CM on the subsequent lactation were not alleviated by bST supplementation. © American Dairy Science Association, 2007.
- Fitzgerald, A. C., Annen-Dawson, E., Baumgard, L. H., & Collier, R. J. (2007). Evaluation of continuous lactation and increased milking frequency on milk production and mammary cell turnover in primiparous holstein cows. Journal of Dairy Science, 90(12), 5483-5489.More infoPMID: 18024739;Abstract: We hypothesized that early-lactation increased milking frequency, in combination with bovine somatotropin (bST), would improve milk yield in continuously milked (CM) primiparous glands through greater mammary epithelial cell (MEC) function, proliferation, and reduced apoptosis (cell turnover). Primiparous cows were randomly assigned to a 2 × 2 × 2 factorial with a splitplot design to either a continuous bST (+bST, n = 4) or no bST (-bST, n = 4) treatment throughout the study. Within each animal, udder halves were randomly assigned to either a CM or a 60-d dry period (control). During late gestation, CM glands were milked twice daily until calving or until spontaneous dry-off. At calving, cows were milked either twice or 4 times daily and udder-half milk yield was recorded until 30 d postpartum. Mammary biopsies were conducted on -19 ± 13, -8 ± 6, +2, +7, and +20 d relative to calving. Postpartum milk yield was reduced in CM udder halves. Reduced milk yield in CM half udders from cows administered bST and milked 4 times daily was 35% compared with 65% in CM half udders in cows not provided bST and milked twice daily. Proliferation of MEC tended to be greater in control vs. CM tissue at 8 ± 6 d prepartum. Mammary epithelial cell proliferation was greater during the prepartum period (d -19, -8) compared with postpartum time points (d 2, 7, 20). Apoptosis of MEC was not affected by dry period length, but was elevated during the first 7 d postpartum compared with levels measured at -19, -8, and 20 d. Bovine somatotropin did not alter MEC turnover in primiparous CM or control glands. The use of increased milking frequency and bST alleviated, but did not prevent, reductions in milk yield of CM primiparous cows. © American Dairy Science Association, 2007.
- Gebremedhin, K. G., Hillman, P. E., Lee, C. N., & Collier, R. J. (2007). Sweating rate of dairy cows under shade and sunny environments. 2007 ASABE Annual International Meeting, Technical Papers, 9 BOOK.More infoAbstract: Sweating rates from live Holstein cows were measured using a closed chamber VapoMeter, and a portable calorimeter. Measurements were made when cows were in shade and exposed to direct sunlight under different air velocities. The effect of color of hair coat on sweating rate was compared. Comparisons of different sweat rate measuring systems were also compared. The sweating rate at zero air velocity using the VapoMeter was 62 g/h-m 2, and the sweating rates at 0.2 and 1.0 m/s measured using the portable calorimeter were 238 g/h-m 2 and 333 g/h-m 2, respectively when ambient temperature was 33°C, relative humidity was 52% and solar load was 740 W/m 2.
- Pezeshki, A., Mehrzad, J., Ghorbani, G. R., Rahmani, H. R., Collier, R. J., & Burvenich, C. (2007). Effects of short dry periods on performance and metabolic status in holstein dairy cows. Journal of Dairy Science, 90(12), 5531-5541.More infoPMID: 18024744;Abstract: To evaluate effects of different dry period lengths on milk yield, milk composition, and energy balance of dairy cows, 122 multiparous and primiparous Holstein dairy cows were used in a completely randomized experimental design with 56-, 42-, and 35-d dry period lengths. Actual dry period lengths for respective treatments (TRT) were 56 ± 5.1 d, 42 ± 2.1 d, and 35 ± 2.7 d. Overall, cows in the 42- and 56-d TRT gained more body condition than those in 35-d TRT during the dry period; however, postpartum body condition score did not change substantially among the TRT. Although from 3 to 210 DIM, differences were not detected in the milk yield of multiparous cows between the 35- and 56-d TRT, primiparous cows in the 35-d TRT produced less milk than those in 56-d TRT. In primiparous cows, the milk production at wk 9, 10, and 11 of lactation was lower in the 35-d compared with the 56-d TRT. Primiparous cows in the 35-d compared with the 56-d TRT produced less milk protein. In the 35-d TRT, serum triglyceride concentration was greater in primiparous cows than in multiparous cows during the peripartum period. Among primiparous cows, those in the 56-d TRT had greater concentrations of nonesterified fatty acids than those in the 35-d TRT during the peripartum period. No significant differences were observed in concentrations of serum glucose, insulin, and insulin-like growth factor-I during early lactation among TRT. There was also no difference among TRT for incidence of metabolic disorders. Thus, this study indicates that shortening the dry period to 35 d may be beneficial in multiparous and overconditioned cows, but not in primiparous cows. © American Dairy Science Association, 2007.
- Settivari, R. S., Spain, J. N., Ellersieck, M. R., Byatt, J. C., Collier, R. J., & Spiers, D. E. (2007). Relationship of thermal status to productivity in heat-stressed dairy cows given recombinant bovine somatotropin. Journal of Dairy Science, 90(3), 1265-1280.More infoPMID: 17297103;Abstract: The responses of lactating Holstein cows to daily administration of bovine somatotropin (bST) were measured at thermoneutrality (Tn) and under both constant and cycled heat-stress conditions to determine the relationship between thermal status and bST-induced shifts in milk production. All tests included a 5-d acclimation period at Tn (18°C), followed by a 2-d increase in ambient temperature to 28.5°C. After d 3, ambient temperature was cycled between 28.5 (day) and 25.5°C (night) for 4 d. Daily injections with either 31 mg of bST or saline began on d 1 of the experiment. Milk production, feed intake, and respiratory rate (RR) were measured daily. Intraperitoneal, telemetric temperature transmitters were used for a continuous measure of core body temperature (T core). Blood samples were collected during each phase to evaluate the changes in serum chemistry in response to bST and heat stress. Following a 15-d recovery, cows were switched across injection treatments and the study was repeated. Milk production decreased by -18.4% below the initial yield at Tn by the end of 7 d of heat challenge. Although a reduction in milk production occurred during heat stress in both groups, milk production was higher in bST-treated cows compared with control cows during periods of constant and cyclic heat. Likewise, bST treatment during the entire period increased the milk-tofeed ratio over the control level by -11.3%. Plasma insulin-like growth factor 1 and serum nonesterified fatty acids accompanied the increased growth hormone level with bST treatment (-122.0 and 88.8%, respectively), whereas plasma urea nitrogen was reduced by -13.3% to reflect the shift to lipid metabolism. There was no difference in Tcore of the treatment and control groups at Tn. Both bST and control cows increased RR and T core above the Tn level by -94.8 and 2.9%, respectively, during constant heat, with a greater increase in T core of bST-treated compared with control cows (-0.6%). The increase in RR during heat stress preceded T core by 1 d for both groups. During cyclic heat, T core decreased by -0.4% compared with constant heat in both the control and bST-treated groups. Bovine somatotropin treatment increased milk production similarly during the Tn and heat-stress periods, -8.3% over the control; however, the bST-induced increase in milk-to-feed ratio was greatest during the continuous and cyclic heat-stress phases, -16.2%. This increase occurred together with the elevation in T core. © American Dairy Science Association, 2007.
- Collier, R. J., Dahl, G. E., & Vanbaale, M. J. (2006). Major advances associated with environmental effects on dairy cattle. Journal of Dairy Science, 89(4), 1244-1253.More infoPMID: 16537957;Abstract: It has long been known that season of the year has major impacts on dairy animal performance measures including growth, reproduction, and lactation. Additionally, as average production per cow has doubled, the metabolic heat output per animal has increased substantially rendering animals more susceptible to heat stress. This, in turn, has altered cooling and housing requirements for cattle. Substantial progress has been made in the last quarter-century in delineating the mechanisms by which thermal stress and photoperiod influence performance of dairy animals. Acclimation to thermal stress is now identified as a homeorhetic process under endocrine control. The process of acclimation occurs in 2 phases (acute and chronic) and involves changes in secretion rate of hormones as well as receptor populations in target tissues. The time required to complete both phases is weeks rather than days. The opportunity may exist to modify endocrine status of animals and improve their resistance to heat and cold stress. New estimates of genotype × environment interactions support use of recently available molecular and genomics tools to identify the genetic basis of heat-stress sensitivity and tolerance. Improved understanding of environmental effects on nutrient requirements has resulted in diets for dairy animals during different weather conditions. Demonstration that estrus behavior is adversely affected by heat stress has led to increased use of timed insemination schemes during the warm summer months to improve conception rates by discarding the need to detect estrus. Studies evaluating the effects of heat stress on embryonic survival support use of cooling during the immediate postbreeding period and use of embryo transfer to improve pregnancy rates. Successful cooling strategies for lactating dairy cows are based on maximizing available routes of heat exchange, convection, conduction, radiation, and evaporation. Areas in dairy operations in which cooling systems have been used to enhance cow comfort, improve milk production, reproductive efficiency, and profit include both housing and milking facilities. Currently, air movement (fans), wetting (soaking) the cow's body surface, high pressure mist (evaporation) to cool the air in the cows' environment, and facilities designed to minimize the transfer of solar radiation are used for heat abatement. Finally, improved understanding of photoperiod effects on cattle has allowed producers to maximize beneficial effects of photoperiod length while minimizing negative effects. © American Dairy Science Association, 2006.
- Collier, R. J., Stiening, C. M., Pollard, B. C., VanBaale, M. J., Baumgard, L. H., Gentry, P. C., & Coussens, P. M. (2006). Use of gene expression microarrays for evaluating environmental stress tolerance at the cellular level in cattle.. Journal of animal science, 84 Suppl, E1-13.More infoPMID: 16582080;Abstract: Selecting domestic animals for tolerance to thermal stress (TS) has been counterproductive, because acclimation involves reducing or diverting metabolizable energy from production to balance heat gain and loss. Ideally, simultaneous selection for increased production and improved thermotolerance is desirable, but to accomplish this at the genomic level the genes associated with acclimation, adaptation, and thermo-tolerance need to be identified. We evaluated the effects of TS on mammary development and gene expression in vitro using a bovine mammary epithelial cell collagen gel culture system. Acute TS was characterized by inhibition and regression of the ductal branches. Gene expression profiling revealed an overall upregulation of genes associated with the stress response and protein repair. In contrast, genes associated with cellular and mammary epithelial cell-specific biosynthesis, metabolism, and morphogenesis were generally downregulated by TS. Future studies will examine the impact of acclimation and adaptation on gene expression to identify those genes associated with acquisition of thermal tolerance.
- Moore, C. E., Kay, J. K., Collier, R. J., VanBaale, M. J., & Baumgard, L. H. (2005). Effect of supplemental conjugated linoleic acids on heat-stressed brown Swiss and Holstein cows. Journal of Dairy Science, 88(5), 1732-1740.More infoPMID: 15829665;Abstract: Heat-stressed dairy cattle are bioenergetically similar to early-lactation cows in that dietary energy may be inadequate to support maximum milk and milk component synthesis. Study objectives were to evaluate whether conjugated linoleic acids- (CLA-) induced milk fat depression (MFD) during heat stress would allow for increased milk and milk component synthesis. In addition, CLA effects on production variables and its ability to induce MFD were compared between Holstein and Brown Swiss cows. Multiparous cows (n = 8, Holstein; n = 5, Brown Swiss) averaging 97 ± 17 d in milk were used in a crossover design during the summer (mean temperature-humidity index = 75.7). Treatment periods were 21 d with a 7-d adaptation period before and between periods. During adaptation periods, all cows received a supplement of palm fatty acid distillate (242 g/d). Dietary treatment consisted of 250 g/d of CLA supplement (78.9 g/d of CLA) or 242 g/d of palm fatty acid distillate to provide equal amounts of fatty acids. The CLA supplement contained a variety of CLA isomers (3.0% trans-8, cis-10; 3.4% cis-9, trans-11; 4.5% trans-10, cis-12; and 4.8% cis-11, trans-13 CLA). Treatments were applied 2x/d with half of the supplement top-dressed at 0600 h and the remainder top-dressed at 1800 h. There was no overall treatment effect on dry matter intake (23.9 kg/d), milk yield (40.0 kg/d), somatic cell count (305,000), protein (2.86%), or lactose content (4.51%) or yields of these milk components. Supplementation with CLA decreased overall milk fat content and yield by 26 and 30%, irrespective of breed. The reduction of milk fat content and yield was greatest on d 21 (28 and 37%, respectively). Energy availability predicted by energy balance was improved with CLA supplementation compared with controls (3.7 vs. 7.1 Mcal/d, respectively). Respiration rate (78 breaths/min) and skin temperature (35.4°C) during maximum heat load were not affected by treatment. The group receiving CLA had higher total milk fat CLA concentration (9.3 vs. 4.9 mg/g). Supplementation with CLA induced MFD and altered milk fat composition similarly between breeds and improved calculated energy balance during heat stress, but had no effect on production measures under these conditions. © American Dairy Science Association, 2005.
- VanBaale, M. J., Ledwith, D. R., Thompson, J. M., Burgos, R., Collier, R. J., & Baumgard, L. H. (2005). Effect of increased milking frequency in early lactation with or without recombinant bovine somatotropin. Journal of Dairy Science, 88(11), 3905-3912.More infoPMID: 16230696;Abstract: Multiparous Holstein cows (n = 300) were assigned to 1 of 2 milking frequency treatments at parturition. Cows were either milked 6 times (6x) or 3 times (3x) daily to determine effects on early lactation milk yields and subsequent lactation persistency with or without use of recombinant bST (rbST). Treatments included a control group milked 3x and 3 groups milked 6x for either the first 7, 14, or 21 days in milk (DIM). Those 4 groups of cows all received rbST starting at 63 DIM. The fifth treatment group was also milked 6x for the first 21 DIM but those cows received no rbST during the entire lactation. All cows returned to 3x milking after their respective treatment periods ended. Cows milked 3x tended to produce more milk (43.2 vs. 41.5 and 41.0 ± 1.1 kg/d) during the first 9 wk of lactation compared with cows milked 6x for 7 or 21 DIM, respectively. Group milk yields after wk 9 averaged 38.3 ± 0.7 kg/d and did not differ among various groups assigned to an increased milking frequency in early lactation. Percentages of milk fat (3.8 ± 0.12%) and protein (2.9 ± 0.06%) did not differ among treatments during the first 9 wk after calving. Early lactation milk yield (41.9 ± 1.2 kg/d) did not differ between the 2 groups of cows milked 6x for 21 DIM. However, cows subsequently administered rbST (at 63 DIM) produced more milk (38.8 vs. 34.2 ± 0.9 kg/d) from wk 10 to 44. The number of cows sent to the hospital during the 305-d trial for mastitis (97), digestive disorders (14), respiratory issues (9), lameness (22), or retained placenta (16), were not affected by treatments (χ2 = 0.49). Under the conditions of this commercial dairy herd in Arizona, increasing milking frequency to 6 times daily for 7 to 21 d at the start of lactation conditions did not increase milk yield nor improve lactation persistency. © American Dairy Science Association, 2005.
- Annen, E. L., Collier, R. J., McGuire, M. A., & Vicini, J. L. (2004). Effects of dry period length on milk yield and mammary epithelial cells. Journal of Dairy Science, 87(SUPPL. 1), E66-E76.More infoAbstract: A dry period, typically 40 to 60 d, between lactations is believed to be required to maximize milk yield in the subsequent lactation. Several hypotheses have been proposed to explain the requirement for the dry period, including (1) replenishment of body reserves, (2) regeneration of mammary tissue, and (3) optimization of benefits from endocrine events near the time of parturition. Continuously milked cows or glands have depressed milk yields but no differences in mammary DNA content or cell number. Nutritional status and endocrine hormones are not factors in reduced milk yield in continuously milked glands. Data from continuous lactation studies suggest that depressed milk yields are due to reduced functionality of mammary parenchyma. There is a need to reevaluate effects of continuous lactation on milk yield in today's high-producing dairy cow because studies on this topic were done using cows achieving peak milk production of 18 to 30. kg/d compared with 45 to 50. kg/d in today's dairy cows. Another factor that has not been considered in conjunction with current milk production levels is the use of bovine somatotropin (bST). Supplementation with bST increases milk yield, improves lactation persistency, and may improve milk yield in continuously milked cows. Future research goals are to examine the effects of continuous lactation in high-producing cows and to determine the effects of bST on milk yield and mammary functionality in continuously milked cows. © 2004 American Dairy Science Association.
- Annen, E. L., Collier, R. J., McGuire, M. A., Vicini, J. L., Ballam, J. M., & Lormore, M. J. (2004). Effect of modified dry period lengths and bovine somatotropin on yield and composition of milk from dairy cows. Journal of Dairy Science, 87(11), 3746-3761.More infoPMID: 15483158;Abstract: Dry periods of 40 to 60 d have been an industry standard because dry periods 12,000 kg of milk and treated with bovine somatotropin (bST). The study used 2 commercial dairies and one university dairy and included 4 treatments. Five multiparous and 5 primiparous cows from each farm were assigned to each treatment: 1) 60-d dry period, label use of bST (60DD); 2) 30-d dry period, label use of bST (30DD); 3) continuous milking, label use of bST (CMLST); and 4) continuous milking with continuous use of bST (CMCST). Per label, bST use started at 57 to 70 d in milk and ended 14 d before drying (60DD and 30DD) or expected calving date (CMLST). In primiparous cows, average milk yields during the first 17 wk of lactation were reduced for cows on treatments 30DD, CMLST, and CMCST vs. the 60DD treatment. (38.3, 35.1, and 37.5 vs. 44.1 ± 1.3 kg/d, respectively). For multiparous cows, respective milk yields did not differ (46.6, 43.4, 46.5, and 47.7 ± 2.1 kg/d). Shortened or omitted dry periods may impede mammary growth in primiparous cows, resulting in reduced milk yield in the subsequent lactation. In contrast, a shortened or omitted dry period with either bST protocol did not alter production in multiparous cows treated with bST. Quality aspects of prepartum milk and colostrum require additional characterization. For multiparous cows, milk income generated for short dry periods or for continuous milking might increase their profitability. At 17 wk of the subsequent lactation, estimates of the cumulative net margins of multiparous cows on the 30DD treatment and continuous milking treatments exceeded those of cows on the 60DD treatment by $40 to $60 per cow.
- Collier, R. J., Annen, E. L., & Fitzgerald, A. C. (2004). Prospects for zero days dry. Veterinary Clinics of North America - Food Animal Practice, 20(3 SPEC. ISS.), 687-701.More infoPMID: 15471631;Abstract: Recent studies in high-producing dairy cows have demonstrated the dry period requirement is greatly influenced by parity and management practice. Multiparous cows that were continuously milked and treated with bST demonstrated negligible production losses in the next lactation. First-lactation heifers, however, demonstrated large reductions in milk yield. These reductions were not overcome by using bST or IMF the next lactation. No studies have been performed examining use of LDPP or SDPP in combination with bST and IMF on the dry-period requirement. Cows that are continuously milked demonstrated higher feed intakes during the peripartum period, which may greatly improve metabolic health. Future studies must examine potential benefits of continuous milking on health in the next lactation.
- Suchyta, S. P., Sipkovsky, S., Kruska, R., Jeffers, A., McNulty, A., Coussens, M. J., Tempelman, R. J., Halgren, R. G., Saama, P. M., Bauman, D. E., Boisclair, Y. R., Burton, J. L., Collier, R. J., DePeters, E. J., Ferris, T. A., Lucy, M. C., McGuire, M. A., Medrano, J. F., Overton, T. R., , Smith, T. P., et al. (2004). Development and testing of a high-density cDNA microarray resource for cattle. Physiological Genomics, 15, 158-164.More infoPMID: 13130080;Abstract: A cDNA microarray resource has been developed with the goal of providing integrated functional genomics resources for cattle. The National Bovine Functional Genomics Consortium's (NBFGC) expressed sequence tag (EST) collection was established in 2001 to develop resources for functional genomics research. The NBFGC EST collection and microarray contains 18,263 unique transcripts, derived from many different tissue types and various physiologically important states within these tissues. The NBFGC microarray has been tested for false-positive rates using self-self hybridizations and was shown to yield robust results in test microarray experiments. A web-accessible database has been established to provide pertinent data related to NBFGC clones, including sequence data, BLAST results, and ontology information. The NBFGC microarray represents the largest cDNA microarray for a livestock species prepared to date and should prove to be a valuable tool in studying genome-wide gene expression in cattle.
- Hasler, J. F., Bilby, C. R., Collier, R. J., Denham, S. C., & Lucy, M. C. (2003). Effect of recombinant bovine somatotropin on superovulatory response and recipient pregnancy rates in a commercial embryo transfer program. Theriogenology, 59(9), 1919-1928.More infoPMID: 12600729;Abstract: Recombinant bovine somatotropin (rbST) has been shown to increase follicular growth in cattle and some studies have demonstrated an increase in superovulatory response for rbST-treated cows. Pregnancy rates have also been shown to increase when rbST was administered around the time of insemination or prior to embryo transfer. The application of rbST for the purpose of increasing superovulatory responses of donor cows and increasing pregnancy rates of recipient heifers was tested in a commercial embryo transfer program. In Experiment 1, embryo donor cows (n = 56) underwent three cycles of control superovulation (two before and one after weaning) and subsequently underwent up to four additional superovulations while being treated with either rbST (500 mg sustained-release rbST; Posilac, Monsanto, St. Louis, MO; n = 28) or excipient (control; n = 28) once every 14 days. In Experiment 2, lactating embryo donor cows (n = 37) underwent a control superovulation and then underwent a superovulation while lactating and being treated with either rbST (n = 16) or excipient (n = 21). In Experiment 3, embryo recipient heifers that were being implanted with either in vitro or in vivo produced embryos were treated with either rbST (n = 146) or excipient (n = 143) at the time of embryo transfer. Treatment of non-lactating (Experiment 1) or lactating (Experiment 2) donor cows with rbST during repeated superovulation did not affect the number of corpora lutea, the sum of transferable embryos, degenerate embryos, and unfertilized oocytes, or the number of transferable embryos. Treatment of recipient heifers with rbST (Experiment 3) did not affect pregnancy rates for either in vitro or in vivo produced embryos. We conclude that superovulatory response and pregnancy rates (respectively) are similar to control for rbST-treated cows undergoing repeated superovulations and rbST-treated recipient heifers treated at the time of embryo transfer. © 2002 Elsevier Science Inc. All rights reserved.
- Kelsey, J. A., Corl, B. A., Collier, R. J., & Bauman, D. E. (2003). The effect of breed, parity, and stage of lactation on conjugated linoleic acid (CLA) in milk fat from dairy cows. Journal of Dairy Science, 86(8), 2588-2597.More infoPMID: 12939083;Abstract: Dairy products are the main source of conjugated linoleic acid (CLA), a functional food component with health benefits. The major source of cis-9, trans-11 CLA in milk fat is endogenous synthesis via Δ9- desaturase from trans-11 18:1, with the remainder from incomplete rumen biohydrogenation of linoleic acid. Diet has a major influence on milk fat CLA; however, effects of physiological factors have received little attention. Our objectives were to examine milk fat content of CLA and the CLA-desaturase index with regard to: 1) effect of breed, parity, and stage of lactation, and 2) variation among individuals and the relationship to milk and milk fat. Holstein (n = 113) and Brown Swiss (n = 106) cows were fed a single diet and milk sampled on the same day to avoid confounding effects of diet and season. Frequency distributions demonstrated that milk fat content of CLA and CLA-desaturase index varied over threefold among individuals, and this needs to be considered in the design of experiments. Holsteins had a higher milk fat content of CLA and CLA-desaturase index, but breed differences were minor. Parity and days in milk also had little or no relationship to the individual variation for these two CLA variables. Breed, parity, and days in milk accounted for
- Kajimura, S., Uchida, K., Yada, T., Riley, L. G., Byatt, J. C., Collier, R. J., Aida, K., Hirano, T., & Grau, E. G. (2002). Stimulation of insulin-like growth factor-I production by recombinant bovine growth hormone in Mozambique tilapia, Oreochromis mossambicus. Fish Physiology and Biochemistry, 25(3), 221-230.More infoAbstract: We have previously reported growth-promoting effects of recombinant bovine growth hormone (rbGH) in Mozambique tilapia, Oreochromis mossambicus, after 4 weekly injections or a single injection of slow-releasing formulation (Posilac®) (Leedom et al. 2002). In order to obtain further understanding of the role of the growth hormone (GH)-insulin-like growth factor-I (IGF-I) axis in growth in the tilapia, the effects of rbGH on plasma and mRNA levels of IGF-I were examined. Plasma IGF-I levels were significantly increased after rbGH and Posilac® injections, and a significant correlation was observed between plasma IGF-I levels, body length and mass in both treatments. IGF-I mRNA levels in the liver and in the skeletal muscle were also significantly increased after rbGH and Posilac® injections, indicating that IGF-I gene expression in these tissues is under control of circulating GH. IGF-I mRNA levels in the gill were not affected by treatment. Liver IGF-I mRNA levels were significantly correlated with body length and with body mass after rbGH and Posilac® injections. These results indicate that the growth-promoting effect of rbGH in this species is mediated to a significant extent via its stimulation of hepatic production of IGF-I and the resulting increase in plasma IGF-I, and also possibly through locally produced IGF-I in the skeletal muscle, acting in a paracrine or autocrine fashion.
- Leedom, T. A., Uchida, K., Yada, T., Harold, N., Byatt, J. C., Collier, R. J., Hirano, T., & Grau, E. G. (2002). Recombinant bovine growth hormone treatment of tilapia: Growth response, metabolic clearance, receptor binding and immunoglobulin production. Aquaculture, 207(3-4), 359-380.More infoAbstract: Experiments were performed to examine the growth-promoting effects of recombinant bovine growth hormone (rbGH) in the euryhaline tilapia (Oreochromis mossambicus). A radioreceptor assay using a crude membrane preparation of tilapia liver revealed that rbGH was about 100-fold less potent than native tilapia GH (tGH) in displacing 125I-labeled tGH. Bovine prolactin (bPRL) was equipotent to bovine GH indicating that the GH receptor of tilapia does not distinguish mammalian GH from mammalian PRL. When juvenile tilapia, weighing 1 g, were maintained at 28°C and received intraperitoneal injection of rbGH at doses of 0.1, 1 or 10 μg/g weekly for 8 weeks, no significant effect on growth was observed. A second experiment examined weekly doses ranging from 1 to 50 μg/g for 16 weeks, using 1 g fish maintained at 23°C. rbGH (50 μg/g) significantly increased growth after 14 and 16 weeks, although the growth rate was significantly less than those held at 28°C. More pronounced growth-promoting effects were observed, however, when fish weighing 5 g and held at 29°C were injected with rbGH at doses of 100 and 1000 μg/g once a week for 4 weeks. A single injection of a sustained-release formulation of rbGH (Posilac®, 100 and 1000 μg/g) also elicited growth-promoting effects in fish weighing 4 g and kept at 29°C. Treatment with rbGH, Posilac® or bovine serum albumin (BSA) elicited significant increases in plasma levels of immunoglobulin (IgM) in a dose-dependent manner. By contrast, there was no change in plasma levels of lysozyme activity in rbGH- or Posilac®-injected fish compared with controls. An uptake and clearance study confirmed a slower decline in circulating levels of rbGH following Posilac® injection compared with rbGH in saline. There was no change in plasma concentration of tGH after rbGH treatment, indicating that GH secretion from the tilapia pituitary was unaffected by high plasma levels of rbGH. The relative refractoriness of juvenile tilapia to growth-promoting effects of rbGH compared with that of other species may be due to the specific nature of the tGH receptor in recognizing the homologous hormone. © 2002 Elsevier Science B.V. All rights reserved.
- Collier, R. J., & Bauman, D. E. (2001). Re: Re: Role of the insulin-like growth factors in cancer development and progression . Journal of the National Cancer Institute, 93(11), 876-.More infoPMID: 11390539;
- Collier, R. J., Byatt, J. C., Denham, S. C., Eppard, P. J., Fabellar, A. C., Hintz, R. L., McGrath, M. F., McLaughlin, C. L., Shearer, J. K., Veenhuizen, J. J., & Vicini, J. L. (2001). Effects of sustained release bovine somatotropin (sometribove) on animal health in commercial dairy herds. Journal of Dairy Science, 84(5), 1098-1108.More infoPMID: 11384036;Abstract: The health of dairy cows given bovine somatotropin (bST) for one lactation was evaluated in 28 commercial herds located in four regions of the United States. At least six herds were in a region and at least one herd/region contained fewer than 60 cows. Cows (n = 1213) were assigned randomly to control or bST groups and were treated beginning in wk 9 to 10 of lactation and every 14 d until dry-off or d 400 of lactation. Management was according to site practices. Cows were observed for health-related signs by farm personnel daily and by the herd veterinarian biweekly. Average 305-d test-day milk yields were 932 kg greater for bST-treated cows. Pregnancy rates, days open, twinning, cystic ovaries, or abortions were unaffected by treatments. Supplementation of cows with bST had no effect on total mastitis cases, total days of mastitis, duration of mastitis, or the odds ratio of a cow to develop mastitis. Cows supplemented with bST used more medications for health events other than mastitis. This usage was associated primarily with treatments for disorders of the foot and hock. Supplemented cows had a slight increase in foot disorders. There was no effect of supplementation with bST on culling from the herd or removal from study. Overall, the results confirm that label directions for bST are adequate for safe use under field conditions. All clinical signs observed in this study occur normally in dairy herds and were managed in cows supplemented with bST.
- Collier, R. (2000). Regulation of rbST in the US. AgBioForum, 3(2-3), 156-163.More infoAbstract: In the United States (US) and European Union (EU) the regulatory and commercialization process for recombinant bovine somatotropin (rbST) had widely differing outcomes. Although the regulatory process in both locations was completed in 1993 the commercialization of rbST in the US has been highly successful while completely failing in the EU. This paper examines these events from the US perspective and concludes that reasons for the difference in commercial success lie in the cultural, regulatory, and political background differences between the two world locations.
- Bauman, D. E., Everett, R. W., Weiland, W. H., & Collier, R. J. (1999). Production responses to bovine somatotropin in northeast dairy herds. Journal of Dairy Science, 82(12), 2564-2573.More infoPMID: 10629802;Abstract: The commercial response to bovine somatotropin was examined in northeast dairy herds from 1990 to 1998 (4-yr preapproval and 4-yr postapproval). With DHI records and Monsanto customer files, a control group (never purchased Posilac) and a bovine somatotropin (bST) group (used on at least 50% of cows) were identified. A total of 340 herds were involved and, over the 8-yr period, there were over 80,000 cows, 200,000 lactations, and 2 million test days. Herd management comparisons demonstrated the response to bST was relatively constant each year of the postapproval period. Assuming 100% of cows were supplemented, response to bST over a 305-d lactation equaled 894 kg of milk, 27 kg of milk fat, and 31 kg of milk protein. Comparisons of lactation curves were used to identify where the bST response occurred in the lactation cycle. Analysis demonstrated the responses in milk, milk fat, and protein yield were minimal in the early phase of lactation, and then gradually increased until reaching a plateau over the last half of the lactation cycle. Persistency of lactation was also improved by bST, indicating the opportunity exists to extend lactation with combined use of bST and altered reproductive management. Average age and days in milk did not differ between control and bST herds. Thus, stayability and herd-life of animals were not altered by bST treatment. Somatic cell count (SCC) linear scores were minimally affected in herds utilizing bST and the pattern of SCC over the lactation cycle was unaffected. Overall bST improved lactation yield and persistency consistently over the 4-yr postapproval period with no effects on cow stayability and herd-life.
- Collier, R. J. (1999). Debate continues on recombinant bovine somatotropin . Lancet, 354(9179), 684-.More infoPMID: 10466700;
- Byatt, J. C., Sorbet, R. H., Eppard, P. J., Curran, T. L., Curran, D. F., & Collier, R. J. (1997). The Effect of Recombinant Bovine Placental Lactogen on Induced Lactation in Dairy Heifers. Journal of Dairy Science, 80(3), 496-503.More infoPMID: 9098799;Abstract: The primary objective of this study was to determine whether bovine placental lactogen stimulated additional mammary growth as assessed by milk yield from a lactation induced by steroids. Pubertal, nonpregnant Holstein heifers (n = 23) were given daily subcutaneous injections of estradiol-17β (0.05 mg/kg) and progesterone (0.25 mg/kg) for 7 d to initiate mammary growth. Prolactin secretion was suppressed in all heifers via bromocriptine, which was administered until d 15. Heifers were treated with either placental lactogen (40 mg/d; n = 12) or water (control group; n = 11) for 18 d. Lactation was induced by daily injection of dexamethasone for 3 d and twice daily injections of recombinant bovine prolactin for 5 d starting on d 18. From 3 to 8 wk of lactation, milk yield of heifers treated with placental lactogen was numerically higher (22%) than the yield of control heifers, but the difference was not significant because of the high coefficient of variation. Daily injection of bovine somatotropin (d 57 to 66 of lactation) increased milk yield of both groups and stimulated a greater numerical increase in milk yield for heifers that were treated with placental lactogen. These results support the hypothesis that bovine placental lactogen is mammogenic and is one of the factors that regulates mammary growth during pregnancy.
- Eppard, P. J., White, T. C., Sorbet, R. H., Weiser, M. G., Cole, W. J., Hartnell, G. F., Hintz, R. L., Lanza, G. M., Vicini, J. L., & Collier, R. J. (1997). Effect of Exogenous Somatotropin on Hematological Variables of Lactating Cows and Their Offspring. Journal of Dairy Science, 80(8), 1582-1591.More infoPMID: 9276796;Abstract: Eighty-two lactating Holstein cows in their first, second, or third lactation received either one, three, or five concurrent i.m. injections of a unit dose (0.6 g) of zinc methionyl bovine somatotropin (bST) or five doses of the vehicle. Injections were administered at 14-d intervals from 60 ± 3 d postpartum until the end of lactation or until necropsy. Thirty-eight cows were continued on the treatment for a 2nd yr. Blood samples were collected at wk -2, -1, 3, and 7 relative to the start of treatment and then every 8 wk (yr 1) or 4 wk (yr 2) thereafter. Untreated cows that were included in a survey of the resident herd were bled at wk 7 or 8, wk 10 or 11, and wk 13 or 14 of lactation and every 4 or 8 wk thereafter. Calves were bled within 72 h of birth and at approximately 5 wk of age. Most parameters associated with erythrocytes were decreased mildly in cows that were treated with bST. However, data remained within generally accepted reference ranges, and changes were not of clinical importance. Decreased hematocrit was not associated with increased hemolysis, hemodilution, or clinical anemia. No morphological lesions related to treatment were noted in the bone marrow or spleen; bST did not affect the incidence of immature cell types. Energy and protein balances did not significantly affect the hematological results of the cows. Calves generally were unaffected by bST treatment of the dam, but heavier calves had higher parameters associated with erythrocyte and lymphocyte counts than did calves with lower body weight. Exogenous bST treatment caused predictable changes in hematological parameters of dairy cows.
- Elsasser, T. H., Richards, M., Collier, R., & Hartnell, G. F. (1996). Physiological responses to repeated endotoxin challenge are selectively affected by recombinant bovine somatotropin administration to calves. Domestic Animal Endocrinology, 13(1), 91-103.More infoPMID: 8625619;
- Eppard, P. J., Veenhuizen, J. J., Cole, W. J., Comens-Keller, P., Hartnell, G. F., Hintz, R. L., Munyakazi, L., Olsson, P. K., Sorbet, R. H., White, T. C., Baile, C. A., Collier, R. J., Goff, J. P., & Horst, R. L. (1996). Effect of Bovine Somatotropin Administered to Periparturient Dairy Cows on the Incidence of Metabolic Disease. Journal of Dairy Science, 79(12), 2170-2181.More infoPMID: 9029355;Abstract: Thirty-eight dry, pregnant Jersey cows were assigned to diet and bST treatment in a 2 × 2 factorial design. During the dry period, half of the cows were fed a normal TMR (0.4% Ca; 0.3 to 0.4% P), and half of the cows were fed a high Ca TMR (1.5 to 1.6% Ca; 0.4 to 0.7% P). The high Ca diets were designed to induce milk fever and were relatively cationic (194 to 293 meq/kg) compared with the normal diets (-131 to 30 meq/kg). A standard dairy diet was fed to all cows postcalving. Cows received subcutaneous injections of either an oil-based excipient or 500 mg of bST in an oil-based excipient every 14 d from 28 d before expected calving until approximately 14 d postcalving. Peripartal bST treatment decreased the incidence of clinical mastitis, did not affect incidence of milk fever, and increased the duration, but not the incidence, of ketosis in mature Jersey cows. Blood data confirmed the clinical responses and indicated that treated cows mobilized more bone Ca than did controls, as was evidenced by increased hydroxyproline concentrations. Treatment with bST did not affect blood concentrations of 1,25-dihydroxyvitamin D, Ca, or Mg. High Ca diets increased the incidence of milk fever and downer cow syndrome compared with normal diets. The effect of bST on mastitis and milk production must be considered as preliminary given the small size of the study. Although bST treatment increased Ca mobilization, the effect was insufficient to prevent milk fever in this model.
- Ganguli, S., Lynn, H. u., Menke, P., Collier, R. J., & Gertler, A. (1996). Nuclear accumulation of multiple protein kinases during prolactin-induced proliferation of Nb2 rat lymphoma cells. Journal of Cellular Physiology, 167(2), 251-260.More infoPMID: 8613465;Abstract: Intracellular kinases play important roles in signal transduction and are involved in the surface receptor-mediated regulation of cellular functions, including mitogenesis. In the present study, we examined the possible involvement of various protein kinases in the passage of a mitogenic signal from the cell surface to the nucleus of Nb2 cells, a rat nodal lymphoma cell line in which prolactin is a mitogen. Following a prolactin challenge, various kinase activities were monitored at short intervals in different cellular fractions over a 60 min period. Protein kinase C (PKC) activity in the cytosolic fraction rapidly declined to 50% of its original activity within the first 30 min, while PKC activity in the nuclear fractions increased sharply, reaching its highest level by 30 min following a prolactin challenge. There were also increases in both casein kinase and protein tyrosine kinase (PTK) activities in the nuclear fractions during the first 30 min following a prolactin challenge that paralleled PKC activity. The activities of all three kinases declined thereafter, reaching levels close to their respective basal Values by 60 min following initiation of prolactin treatment. These observations suggest the possibility that multiple protein kinases may be involved in mitogenic signal transduction for prolactin in Nb2 cells.
- Heap, D., Collier, R. J., Boyd, C. K., & Lucy, M. C. (1996). Expression of alternate growth hormone receptor messenger RNA in ovary and uterus of cattle. Domestic Animal Endocrinology, 13(5), 421-430.More infoPMID: 8886595;Abstract: Growth hormone (GH) receptor mRNA is found within the corpus luteum and endometrium of cattle. However, binding sites for placental lactogen (PL) but not GH are found within these tissues. The objectives were to isolate cDNA for the GH receptor within the reproductive tissues of cattle and to examine these cDNA as potential variants of the GH receptor that bind PL. Ten cDNA clones were isolated from a bovine endometrial cDNA library with a 32P- labeled cDNA of the GH receptor extracellular domain. On the basis of restriction enzyme digestion, 2 of the 10 cDNA clones contained exon 1. The DNA sequence of these clones was determined by dideoxy nucleotide sequencing. The exon I DNA sequence of each clone (exon 1B) was different from the previously reported exon I for the bovine GH receptor cDNA isolated from liver (exon 1A). Analyses of these cDNA sequences showed that exon lB contained significant homology with placental forms of the GH receptor found in mouse and human. Unlike the human cDNA, the bovine cDNA isolated from endometrium contained an intact third exon. Amplification of GH receptor mRNA by reverse transcriptase polymerase chain reaction, with exon 1A- and 1B- specific forward primers, showed that exon lB was expressed in liver, corpus luteum, ovary, endometrium, and myometrium. Exon 1A was found almost exclusively in liver, and little was found in reproductive tissues. The predicted initiation of protein coding for the GH receptor was within the second exon and was not changed by the splicing of the alternate first exon. This suggests that the alternate mRNA results in the expression of intact GH receptor protein that is similar to that found within liver. Alternative promoters (1B) may control the expression of the receptor outside the liver. Furthermore, mechanisms other than the differential splicing of GH receptor protein may dictate the specificity of PL binding within the endometrium and corpus luteum.
- Houseknecht, K. L., Bauman, D. E., Vernon, R. G., Byatt, J. C., & Collier, R. J. (1996). Insulin-like growth factors-I and -II, somatotropin, prolactin, and placental lactogen are not acute effectors of lipolysis in ruminants. Domestic Animal Endocrinology, 13(3), 239-249.More infoPMID: 8738865;Abstract: The acute regulation of lipolysis in the adipose tissue of ruminants was evaluated with lactating cows (n = 4) and growing ewe lambs (n = 11). Subcutaneous adipose tissue was obtained by biopsy or at slaughter and was incubated with varying concentrations of biologically active insulin-like growth factors-I and -II (IGF-I, IGF-II), somatotropin (ST), prolactin (PRL), or placental lactogen (PL) to determine the effect of these hormones on lipolysis. Complimentary studies were conducted to examine the effects of IGF-I and IGF-II on the acute regulation of lipolysis in adipose tissue from lactating ewes and wethers under a variety of incubation conditions. Isoproterenol (ISO), a β-adrenergic agonist known to rapidly stimulate lipolysis, was used as a positive control. Incubation with ISO for 3 hr resulted in a significant increase in the rates of lipolysis. However, there was no stimulation of lipolysis over the 3-hr incubation at any concentration or under any conditions for IGF-I or IGF-II. Furthermore, ST, PRL, or PL had no acute effects on the rates of lipolysis in adipose tissue. These data demonstrate that IGF-I, IGF-II, ST, PRL, and PL are not acute effectors of the lipolytic rate in the adipose tissue of ruminants.
- Kirby, C. J., Thatcher, W. W., Collier, R. J., Simmen, F. A., & Lucy, M. C. (1996). Effects of growth hormone and pregnancy on expression of growth hormone receptor, insulin-like growth factor-I, and insulin-like growth factor binding protein-2 and -3 genes in bovine uterus, ovary, and oviduct. Biology of Reproduction, 55(5), 996-1002.More infoPMID: 8902209;Abstract: The effects of growth hormone (GH) and pregnancy on insulin-like growth factor (IGF)-I, IGF binding protein (IGFBP)-2, and IGFBP-3 mRNA in reproductive tissues were studied in cattle. Lactating dairy cows were inseminated at estrus and treated with 25 mg/day GH (n = 8) or saline (n = 8) for 16 days. Corpus luteum (CL), ovary (CL removed), oviduct, endometrium, and myometrium were collected at the end of treatment. Messenger RNA for GH receptor, IGF-I, IGFBP-2, IGFBP-3, and actin were measured by nuclease protection assays. The CL contained more GH receptor mRNA than the other reproductive tissues examined. Expression of IGF-I mRNA was highest in myometrium, with lower amounts found in endometrium; the CL expressed the least amount of IGF-I mRNA. The IGFBP-2 mRNA was most abundant in endometrium and least abundant in CL. Expression of IGFBP-3 mRNA was detected in all reproductive tissues examined. However, endometrium, a tissue that expressed the most IGFBP-2 mRNA, had the lowest amount of IGFBP-3 mRNA. The GH receptor mRNA was decreased in cows treated with GH whereas the mRNA for IGF-I, IGFBP- 2, or IGFBP-3 was not changed. In the reproductive tissues evaluated, cows that contained a conceptus at tissue collection (pregnant) had higher amounts of IGF-I mRNA than did nonpregnant cows. In summary, the level of mRNA encoding GH receptor, IGF-I, IGFBP-2, and IGFBP-3 varied within the tissues examined, suggesting that these genes may play a variety of roles in the bovine female reproductive tract. Supplemental GH failed to change the expression of IGF-I, IGFBP-2, and IGFBP-3 mRNA, possibly because of low GH receptor mRNA levels in tissues other than CL. A direct action of GH on IGF- I, IGFBP-2, or IGFBP-3 gene expression within cow reproductive tissues was not supported because the amount of IGF-I, IGFBP-2, or IGFBP-3 mRNA was not altered by GH.
- Adriaens, F. A., Hard, D. L., Miller, M. A., Phipps, R. H., Sorbet, R. H., Hintz, R. L., & Collier, R. J. (1995). Pituitary response to thyrotropin, corticotropin, and gonadotropin-releasing hormones in lactating cows treated with sometribove for a fourth consecutive lactation. Domestic Animal Endocrinology, 12(4), 301-316.More infoPMID: 8575163;Abstract: The effect of chronic treatment with recombinant methionyl bovine somatotropin (USAN, sometribove) on anterior pituitary secretions and its target organs was investigated in six control and six sometribove-treated British Friesian cows. Cows averaged 112 and 119 d postpartum in their fourth lactation of treatment and, except for one control, had active corpora lutea. During each lactation, treated cows received sometribove injections (500 mg) every 2 wk (injection cycle) starting 60 ± 3 d postpartum. On Day 9 of one injection cycle, blood was sampled for 390 min, starting 30 min before an intravenous injection of thyrotropin (TRH, 0.33 μg/kg), corticotropin (100 μg), and gonadotropin (GnRH, 200 μg)-releasing hormones. Baseline somatotropin (bST) and adrenocorticotropin (ACTH) were higher in sometribove-treated cows vs. controls (3.27 vs. 1.03 ng/ml and 35.24 vs. 19.28 pg/ml, respectively). Baseline total thyroxine, free thyroxine, triiodothyronine, prolactin, follicle stimulating and luteinizing hormones, estradiol, and progesterone (P4) were similar across treatments. Circulating cortisol levels did not differ between control and sometribove cows, indicating a reduced adrenal ACTH responsiveness in the latter. Releasing factors induced similar changes across treatments in hormones studied with the following exceptions: a bST spike was seen in control cows only, cortisol response to ACTH was reduced in treated cows, and a significantly higher P4 concentration was detected in the plasma of sometribove-treated cows, suggesting increased ovarian responsiveness to GnRH-stimulated P4 output. The study demonstrated reduced bST response to TRH, consistent with physiologic feedback mechanisms, whereas the release profiles of the other pituitary hormones were unaffected. Target tissue responses affected by chronic sometribove treatment appear to be adrenal cortisol and ovarian P4 output. © 1995.
- Byatt, J. C., & Collier, R. J. (1995). Specific endometrial binding sites for bovine placental lactogen are antigenically similar to the growth hormone receptor. Proceedings of the Society for Experimental Biology and Medicine, 210(1), 20-24.More infoPMID: 7675794;Abstract: Bovine liver growth hormone receptors bind both bovine growth hormone (bGH) and bovine placental lactogen (bPL) with high affinity (K(d) = 1.4 x 10-11 M and 3.0 x 10-11 M, respectively). By contrast, the uterine endometrium of pregnant cattle has high-affinity (K(d) = 8.0 x 10-11 M) binding sites for bPL but, displays negligable binding of bGH. A polyclonal antiserum raised against the extracellular domain of the bGH receptor, was used to determine if there was antigenic similarity between the liver bGH receptor and the endometrial bPL binding site(s). On Western blots, this antiserum displayed cross-reactivity with a 180,000-mol wt protein (nonreducing conditions) in detergent-solubilized extracts of microsomal membranes from both tissues. However, different detergents (Triton X-100 for endometrium and 3-[(3-cholamidopropyl)dimethylammonio]-1-propane-sulfonate [CHAPS] for liver) were required to solubilize the cross-reacting protein in the two tissues. The purified immunoglobulin fraction from this same antiserum also blocked binding of [125I]bPL to microsomal membrane preparations from both liver and endometrium. These results indicate that the endometrial binding site for bPL is antigenically similar to the bGH receptor and raise the possibility that it may be a modified GH receptor.
- Heap, D., Lucy, M. C., Collier, R. J., Boyd, C. K., & Warren, W. C. (1995). Rapid communication: nucleotide sequence of the promoter and first exon of the somatotropin receptor gene in cattle.. Journal of animal science, 73(5), 1529-.More infoPMID: 7665385;
- Lucy, M. C., Thatcher, W. W., Collier, R. J., Simmen, F. A., Ko, Y., Savio, J. D., & Badinga, L. (1995). Effects of somatotropin on the conceptus, uterus, and ovary during maternal recognition of pregnancy in cattle. Domestic Animal Endocrinology, 12(1), 73-82.More infoPMID: 7542581;Abstract: Effects of recombinant bovine somatotropin (rbST) on ovarian and uterine function and the production of components of the insulin-like growth factor (IGF) system were examined during the period of maternal recognition of pregnancy in cattle. Lactating dairy cows were treated with 25 mg/d rbST (n = 8) or saline (n = 8) for 16 d after estrus. Ovaries, uteri, and conceptuses were collected on Day 17 after estrus. The length (millimeters) of the conceptus was recorded. The concentration of IGF-I and the content of IGF-binding proteins (BP) in uterine flushings were determined. Corpora lutea (CL) were weighed, and the number of follicles (≥2 mm in diameter) were counted. Follicular fluid from the largest and second-largest follicles was assayed for the concentration of IGF-I, IGFBP, progesterone, and estradiol. The length of the conceptus and the total amount of IGF-I in uterine fluid were similar for rbST and control. Recombinant bST increased 1) the weight of the CL, 2) the number of largest follicles (10 to 15 mm in diameter), 3) the concentration of IGF-I in the follicular fluid, 4) the follicular fluid content of IGFBP of the largest estrogenic follicle, and 5) the quantity of IGFBP in uterine flushings. The concentration of progesterone in the follicular fluid tended to be increased in rbST-treated cows, whereas the concentration of estradiol was similar to that of control cows. The concentration of progesterone in plasma was similar for rbST compared with control. In conclusion, the administration of rbST in lactating dairy cows for 16 d after estrus did not alter the growth of the conceptus collected on Day 17. The greatest responses to rbST were found within the ovary, where rbST increased the weight of the CL and altered the amount of IGF-I and IGFBP in the follicular fluid. © 1995.
- Vicini, J. L., Hartnell, G. F., Veenhuizen, J. J., Collier, R. J., & Munyakazi, L. (1995). Effect of supplemental dietary fat or protein on the short-term milk production response to bovine somatotropin.. Journal of dairy science, 78(4), 863-871.More infoPMID: 7790577;Abstract: Effects of supplemental energy or protein on the milk production response to bST administration were examined in two separate trials. In trial 1, 40 cows were used in a 2 x 2 factorial, completely randomized design to determine the effects of bST and fat supplementation. The study consisted of a 7-d pretreatment period and a 42-d treatment period. Fat was top-dressed at 3.0 Mcal/d of NEL, and bST was administered. Supplemental fat had no effect on milk production, and NEL intakes were unaffected. Administration of bST increased milk production by 7.1 kg/d, and the milk production response was unaffected by supplemental fat. In trial 2, 4 cows were used in four periods with a 2 x 2 factorial arrangement in which water or casein was infused into the abomasum of cows fed for ad libitum intake or at 80% of their requirements. Diets and infusions were initiated simultaneously and continued for 11 d. All cows were given bST during the last 5 d. Infusion of water or casein did not alter the milk production response to bST, but restricted feeding reduced the bST response (3.2 vs. 7.2 kg/d). Concentrations of IGF-I in plasma were increased by bST administration, and the increase was greatest for cows fed for ad libitum intake. The milk production response to bST was not increased by additional energy or protein offered to cows fed well-balanced diets.
- Byatt, J. C., Eppard, P. J., Veenhuizen, J. J., Curran, T. L., Curran, D. F., McGrath, M. F., & Collier, R. J. (1994). Stimulation of mammogenesis and lactogenesis by recombinant bovine placental lactogen in steroid-primed dairy heifers. Journal of Endocrinology, 140(1), 33-43.More infoPMID: 7511153;Abstract: A model of induced lactation was modified to examine the effects of bovine prolactin (bPRL) and bovine placental lactogen (bPL) on mammary growth and differentiation. Thirty-two peripubertal, non-pregnant Holstein heifers were given daily s.c. injections of oestradiol (0·05 mg/kg) and progesterone (0·25 mg/kg) for 7 days to initiate mammary growth. Treatment with bromocriptine (40 mg/3 days) reduced serum PRL concentrations to approximately 25% of pretreatment levels, for the duration of the study. On the day following the last steroid injection, groups of eight heifers were given twice daily s.c. injections of either saline (negative control), recombinant bPRL (rbPRL; 80 mg/day) or recombinant bPL (rbPL; 80 and 160 mg/day) for 7 days. At the end of this period (day 15), growth and differentiation of the mammary glands were assessed. Treatment with rbPL increased total mammary DNA above control value by 50 and 60% for the 80 and 160 mg/day doses respectively. However, total DNA was not different for the control and rbPRL-treated groups. The blood serum concentration of α- lactalbumin was measured daily throughout the study and used as an index of mammary differentiation. Both rbPRL and rbPL stimulated mammary differentiation (i.e. induction of milk synthesis), although rbPRL appeared to be more potent than rbPL. These results indicate that rbPL is lactogenic in vivo and strongly suggest that bPL is a mammary mitogen.
- Challacombe, D. N., Wheeler, E. E., Collier, R. J., Clemmons, D. R., Donovan, S. M., & Wilkinson, J. I. (1994). Safety of milk from cows treated with bovine somatotrophin . Lancet, 344(8925), 815-817.More infoPMID: 7993454;
- Collier, R. J., & Hard, D. L. (1994). Monsanto defends itself . Nature, 372(6503), 214-.More infoPMID: 7969460;
- Collier, R. J., Clemmons, D. R., & Donovan, S. M. (1994). Safety of milk from cows treated with bovine somatotrophin.. Lancet, 344(8925), 816-.More infoPMID: 7916092;
- Lucy, M. C., Byatt, J. C., Curran, T. L., Curran, D. F., & Collier, R. J. (1994). Placental lactogen and somatotropin: Hormone binding to the corpus luteum and effects on the growth and functions of the ovary in heifers. Biology of Reproduction, 50(5), 1136-1144.More infoPMID: 8025170;Abstract: The effects of recombinant bovine placental lactogen (rbPL) and recombinant bovine somatotropin (rbST) on development of ovarian follicles and CL were tested in heifers. Estrus (day = 0) was synchronized and heifers were treated (Days 0-21) with either saline (control; n = 7), rbST (25 mg/day; n = 6), or rbPL (50 mg/day; n = 8). Blood was collected daily for analyses of progesterone, estradiol, ST, PL, and insulin-like growth factor (IGF)-I; ultrasound was performed daily for measurement of follicles and CL PL in plasma (mean ± SE; ng/ml) averaged 4.1 ± 0.2 for rbPL-treated heifers, and ST in plasma (ng/ml) averaged 2.7 ± 0.3 for rbST-treated heifers. IGF-I in plasma (ng/ml) was increased for rbST-treated (198 ± 10; p < 0.001) and rbPL treated (143 ± 9; p < 0.06) heifers compared to controls (117 ± 9). After Day 9 of the estrous cycle, heifers treated with rbPL had larger CL (p < 0.001) and more progesterone in plasma (p < 0.001) than controls, whereas rbST-treated heifers were intermediate for these measures. Largest follicles were decreased in size (mm) throughout the estrous cycle for rbPL-treated heifers (12.9 ± 0.4) compared to controls (14.2 ± 0.5; p < 0.06) or heifers given rbST (14.0 ± 0.5; p < 0.11). After Day 17 (preovulatory period), concentrations of estradiol in serum (pg/ml) were decreased for rbST-treated (2.7 ± 0.3; p < 0.01) and rbPL-treated (2.9 ± 0.2; p < 0.02) heifers compared to controls (3.8 ± 0.3). Size of second largest follicles (mm) was increased for heifers given rbST (10.0 ± 0.5) compared to controls (8.2 ± 0.5; p < 0.02) or to heifers given rbPL (8.6 ± 0.4; p < 0.06), and timing of the second follicular wave was earlier for animals given rbST and rbPL compared to controls. Estrous cycle length (days) averaged 20.4 ± 0.8, 21.3 ± 0.8, and 21.5 ± 0.7 for the control, rbST, and rbPL groups, respectively (p > 0.10). From these studies there appeared to be a specific effect of rbPL on development of the CL. Microsomal membranes were prepared from CL tissue to determine whether there were specific binding sites for rbPL. Specific binding of [125I]-rbPL to CL membranes averaged 8.44%, and membrane preparations displayed high-affinity binding sites for rbPL (dissociation constant = 1.0 x 10-11 M; total number of binding sites = 2.2 fmol/mg protein). Specific binding of radiolabeled rbST or recombinant bovine prolactin (rbPRL) was < 0.1% for either ligand. In conclusion, rbPL was stimulatory to the CL and inhibited follicular function in heifers. Responses of the ovary to rbPL were not identical to those for rbST. Therefore, changes in ovarian function during pregnancy may be explained partially by secretion of bPL from the placenta.
- Lucy, M. C., Curran, T. L., Collier, R. J., & Cole, W. J. (1994). Extended function of the corpus luteum and earlier development of the second follicular wave in heifers treated with bovine somatotropin. Theriogenology, 41(2), 561-572.More infoAbstract: Effects of recombinant bovine somatotropin (bST) on growth of the corpus luteum (CL) and development of ovarian follicles were tested. Starting at estrus (Day=0), the following treatments were administered: control (saline injected Days 0 to 19, n=5); bST[0-9] (25 mg bST injected Days 0 to 9, saline injected Days 10 to 19, n=5); bST[10-19] (saline injected Days 0 to 9, 25 mg bST injected Days 10 to 19, n=5); and bST[0-19] (25 mg bST injected Days 0 to 19, n=6). Blood was collected daily for progesterone analysis, and ultrasound examinations were performed daily for measurement of follicles and CL. Compared with the heifers treated with saline, those treated with bST had larger CL and more progesterone during the early (≤ Day 10) and late (Days 15 to 21) phases of the estrous cycle. At mid-cycle (Days 10 to 15), luteal tissue area and progesterone levels were similar for bST- and saline-treated heifers. Ovarian follicular growth was similar for bST- and saline-treated heifers during the first follicular wave. However, during recruitment for the second follicular wave (Days 10 to 14), second largest follicles emerged sooner (P
- White, T. C., Madsen, K. S., Hintz, R. L., Sorbet, R. H., Collier, R. J., Hard, D. L., Hartnell, G. F., Samuels, W. A., Kerchove, G. d., & Adriaens, F. (1994). Clinical mastitis in cows treated with sometribove (recombinant bovine somatotropin) and its relationship to milk yield.. Journal of dairy science, 77(8), 2249-2260.More infoPMID: 7962847;Abstract: Effect of sometribove (methionyl bovine somatotropin) on mastitis in 15 full lactation trials (914 cows) in Europe and the US and 70 short-term studies (2697 cows) in eight countries was investigated. In full lactation studies, sometribove (500 mg/2 wk) was given for 252 d, commencing 60 d postpartum. Although herds varied considerably, incidence of clinical mastitis within a herd was similar for cows receiving control and sometribove treatments. Relative risk analyses indicated no treatment effect, and percentage of mastitis during treatment was similar for control and sometribove groups. A positive linear relationship existed between peak milk yield and mastitis incidence (percentage of cows contracting mastitis or cases per 100 cow days); sometribove treatment did not alter this relationship. Increases in mastitis related to milk yield increase from sometribove or related to genetic selection were similar. When expressed per unit of milk, mastitis incidence declined slightly as milk yield increased; this relationship was not altered by sometribove. No effect on clinical mastitis was observed in 70 commercial herds utilizing sometribove for 84 d. However, effects were significant for stage of lactation and milk yield. Overall, studies represented a wide range of research and commercial situations demonstrating that sometribove had no effect on incidence of clinical mastitis during the lactation of treatment. Furthermore, sometribove did not alter typical relationships between milk yield or herd factors and incidence of clinical mastitis.
- Byatt, J. C., Staten, N. R., Salsgiver, W. J., Kostelc, J. G., & Collier, R. J. (1993). Stimulation of food intake and weight gain in mature female rats by bovine prolactin and bovine growth hormone. American Journal of Physiology - Endocrinology and Metabolism, 264(6 27-6), E986-E992.More infoPMID: 8333524;Abstract: Recombinant bovine prolactin (rbPRL) or bovine growth hormone (rbGH) was administered to mature female rats (10/treatment group) by daily subcutaneous injection for 10 days. Doses ranged from 7 to 5,000 μg/day (0.03-24 mg/kg body wt). Both rbPRL and rbGH increased body weight gain and food intake, but these parameters were increased at lower doses of rbPRL (7-63 μg/day) than rbGH (>190 μg/day). Weight gain and food intake were maximally stimulated by 190 μg/day rbPRL, whereas maximal increased weight gain was obtained with the highest dose of rbGH (5,000 μg/day). Total carcass protein was increased by both hormones; however, protein as a percentage of body weight was unchanged. Similarly, neither rbPRL nor rbGH changed the percentage of carcass moisture. Percentage of body fat was increased by rbPRL but was decreased by rbGH. Weight of the gastrointestinal tract and kidneys was increased by both hormones, but increases were in proportion to body weight gain. These data confirm that ungulate prolactin is a hyperphagic agent in the female rat. In addition, they suggest that, while prolactin stimulates growth in mature female rats, this growth is probably not via a somatogenic mechanism.
- Collier, R. J., McGrath, M. F., Byatt, J. C., & Zurfluh, L. L. (1993). Regulation of bovine mammary growth by peptide hormones: involvement of receptors, growth factors and binding proteins. Livestock Production Science, 35(1-2), 21-33.More infoAbstract: Involvement of the somatotropin (ST)/prolactin(PRL)/placental lactogen (PL) family and their mediators in regulating mammary growth in cattle was evaluated using both in vitro and in vivo models. Mitogenic activity of bovine mammary epithelial cells (BMEC) was not increased by ST, PRL or PL in vitro. Direct infusion of ST but not PRL into mammary glands of late pregnant beef cows increased mammary DNA. Exogenous treatment of steroid-primed dairy heifers with PL increased mammary DNA while PRL treatment resulted in lactogenesis but no detectable increase in mammary DNA. Insulin-like growth factor-I (IGF-I) directly increased BMEC DNA synthesis in vitro and infusion of IGF-I into mammary glands of late pregnant beef cows increased mammary growth. Epidermal growth factor and transforming growth factor-alpha increased the mitogenic response to IGF-I and are likely involved in paracrine regulation of mammary growth. IGF binding proteins are produced and secreted by BMEC and may be autocrine regulators of growth. Collectively, these data indicate that lactogenic hormone receptors are not involved in regulation of mammary growth in cattle. Increased mammary growth following ST and PL treatment was apparently mediated through local production or uptake of IGFs and/or alteration of IGF binding protein concentrations. Presently, it is not clear whether ST and PL act through local as well as distant somatotrophic receptors to alter availability and uptake of IGFs. © 1993.
- Eppard, P. J., White, T. C., Birmingham, B. K., Hintz, R. L., Bentle, L. A., Wood, D. C., Salsgiver, W. J., Rowold, E., Miller, M. A., Ganguli, S., Hale, M. D., Krivi, G. G., Collier, R. J., & Lanza, G. M. (1993). Pharmacokinetics and galactopoietic response to recombinant variants of bovine growth hormone. Journal of Endocrinology, 139(3), 441-450.More infoPMID: 8133211;Abstract: Two studies were designed to examine the pharmacokinetic and galactopoietic potency of three molecular variants of recombinant-derived bovine GH (rbGH): [Met1, Leu127]-bGH, [Ala1, Val127]-bGH and [Ala1, Val127, His133]-bGH. Histidine substitution for arginine at residue 133 of rbGH was shown to impart thrombin resistance. In a Latin square design, nine lactating Holstein cows received a 25 mg rbGH bolus infusion via the jugular vein followed by frequent blood sampling over the next 12 h. The serum GH concentration data were found to fit to a two compartment open model. Neither primary nor secondary kinetic parameter estimates differed significantly (P > 0.05) among the three rbGH variants. Thus, the disposition of GH concentration at time t was described by the equation C(t) = (1295.5 μg/l) (e(-(0.11/min)(t))) + (317.3 μg/l)(e(-(0.03/min)(t))). Overall averages were: area under the curve = 27.1 mg · min per 1, clearance = 0.15 litres/min per 100 kg and volume of distribution of the central compartment = 2.59 litres/100 kg. The t( 1/2 ) for the two compartments averaged 8.2 and 29.1 min. In the second study, 36 lactating Holstein cows received i.m. injections of one of four oil-based formulation treatments: control vehicle or 500 mg of one of the three rbGH variants every 14 days for 42 days. Average and maximum serum GH concentrations and area under the curve estimates were increased by approximately 3-6 μg/l, 5-15 μg/l and 40-90 μg · day per 1 respectively. Ala1, Val127 rbGH treatments elicited greater blood GH concentrations than [Met1, Leu127]-bGH when administered in an oil-based formulation. Blood GH responses did not directly translate into milk response differences, possibly due to differences in biopotency or receptor availability. Thrombin resistance resulting from substitution of histidine at position 127 of rbGH did not affect blood GH pharmacokinetic parameters or milk response over other rbGH variants.
- Hayden, J. M., Williams, J. E., & Collier, R. J. (1993). Plasma growth hormone, insulin-like growth factor, insulin, and thyroid hormone association with body protein and fat accretion in steers undergoing compensatory gain after dietary energy restriction.. Journal of animal science, 71(12), 3327-3338.More infoPMID: 8294284;Abstract: Eighteen Chianina crossbred steers were used to examine the interrelationship between hormonal status and empty body protein (EBPRT) and fat (EBFAT) accretion during an 88-d controlled realimentation (REAL; DMI was adjusted weekly on an individual BW basis) period. Body composition was determined by monitoring endogenous whole-body 40[K]. At the end of restriction (REST) and on d 31 and 59 of REAL blood samples were taken and analyzed for concentrations of growth hormone (GH), IGF-I, IGF-II, insulin (INS), thyroxine (T4), triiodothyronine (T3), reverse triiodothyronine (rT3), nonesterified fatty acids (NEFA), glucose, and urea nitrogen. Depositions of EBPRT and EBFAT were decreased (P < .001) in REST (92 d) animals compared with nonrestricted (NR) controls. During REST, plasma levels of glucose, IGF-I, INS, T4, T3, and rT3 were decreased (P < .05); plasma urea nitrogen (PUN), NEFA, and GH levels were increased (P < .05), and IGF-II concentrations were similar between REST and NR steers. A transient compensatory response in BW gain and protein deposition occurred in repleted steers between d 35 and 62 of REAL. During this period, PUN levels markedly declined (P < .01) in REAL steers and glucose concentration increased (P < .01) to levels similar to those in NR controls. This response prevailed even though apparent digestible nutrients were decreased in repleted animals. During energy repletion, plasma levels of T4, T3, rT3, IGF-I, and INS were positively, and of GH was negatively, correlated with EBPRT and EBFAT gain in repleted animals. Unlike IGF-I, IGF-II was not correlated with compensatory body growth. These results suggest that compensating steers are more metabolically efficient; rapid body tissue gain occurs during a period of reduced nutrient digestibility. Additionally, plasma levels of IGF-I, GH, INS, and thyroid hormones, but not of IGF-II, are markedly affected by alteration of energy intake and are highly correlated with empty body gain and protein deposition in compensating late-maturing steers.
- Lucy, M. C., Collier, R. J., Kitchell, M. L., Dibner, J. J., Hauser, S. D., & Krivi, G. G. (1993). Immunohistochemical and nucleic acid analysis of somatotropin receptor populations in the bovine ovary. Biology of Reproduction, 48(6), 1219-1227.More infoPMID: 8318577;Abstract: Ovaries were analyzed for somatotropin receptor protein and mRNA through use of immunohistochemistry, solution hybridization/nuclease protection, Northern blotting, and reverse transcriptase polymerase chain reaction (RT- PCR). As indicated by immunoperoxidase staining, CL expressed immunoreactive somatotropin receptor (positive stain). Ovarian stroma, connective tissue, endothelium, and erythrocytes did not express somatotropin receptor (negative stain). Within the CL, somatotropin receptor protein was expressed primarily in large luteal cells whereas small luteal cells were negative. Most follicles (1-5 mm, after fixation) were negative for somatotropin receptor. On the basis of solution hybridization/nuclease protection, the mRNA for somatotropin receptor was found in greatest abundance in CL and large luteal cells and was nearly undetectable in small luteal cells or follicles (class 1, 3-5 mm; class 2, 6-9 mm; and class 3, ≥ 10 mm). Northern blotting of mRNA for somatotropin receptor showed expression of somatotropin receptor mRNA transcripts in whole ovary (4.7 and 4.4 kb), CL (4.7 and 4.4 kb), and liver (4.4 kb); and RT-PCR amplified a single amino acid coding region for somatotropin receptor in CL and liver. In summary, somatotropin receptor (both immunoreactive protein and mRNA) is found primarily in the large luteal cell, and lesser amounts of the expressed receptor or its message are found in the follicle. Alternative sizes of mRNA for somatotropin receptor suggest novel mRNA processing in the bovine ovary.
- Lucy, M. C., Hauser, S. D., Eppard, P. J., Krivi, G. G., Clark, J. H., Bauman, D. E., & Collier, R. J. (1993). Variants of somatotropin in cattle: gene frequencies in major dairy breeds and associated milk production. Domestic Animal Endocrinology, 10(4), 325-333.More infoPMID: 7905813;Abstract: The amino acid sequence of bovine somatotropin (bST) varies at position 127 where either valine or leucine is found. The frequencies of leucine127 and valine127 bST gene alleles in cows (n = 302) and sires (n = 70) from major dairy breeds (Holstein, Brown Swiss, Guernsey, Jersey, and Ayrshire) were determined using DNA extracted from whole blood or spermatozoa. A 428 base pair fragment of the bST gene was amplified using polymerase chain reaction (PCR) and variants of the bST gene were detected as polymorphisms by Alu I restriction endonuclease digestion of PCR products. Restriction enzyme DNA fragments for the leucine127 variant were 265, 96, 51, and 16 base pair and for the valine127 variant were 265, 147, and 16 base pair as a polymorphism of bST was present in the 147 base pair DNA fragment. Frequencies of leucine127 and valine127 alleles for cows (n=302) were 1.0 and 0 for Brown Swiss, .93 and .07 for Holstein, .92 and .08 for Guernsey, .79 and .21 for Ayrshire, and .56 and .44 for Jersey, respectively. In Holstein sires used for artificial insemination (n=70), the frequency of leucine127 and valine127 alleles was .96 and .04. Estimates of transmitting ability for milk production tended to be greater for Holstein cows that were homozygous for leucine127 bST and Jersey cows that were homozygous for valine127 bST whereas Holstein sires with different bST genotypes were similar. In summary, frequencies of alleles for the bST gene were not similar in different dairy breeds and estimates of milk production were correlated with bST gene variant in cows but not sires. © 1993.
- McLaughlin, C. L., Byatt, J. C., Hedrick, H. B., Veenhuizen, J. J., Curran, D. F., Hintz, R. L., Hartnell, G. F., Kasser, T. R., Collier, R. J., & Baile, C. A. (1993). Performance, clinical chemistry, and carcass responses of finishing lambs to recombinant bovine somatotropin and bovine placental lactogen.. Journal of animal science, 71(12), 3307-3318.More infoPMID: 8294282;Abstract: Bovine placental lactogen (PL) is a partial somatotropin agonist in the cow and decreases urea nitrogen, indicating increased nitrogen retention. In the present study, the somatogenic effects of bovine PL (bPL; 4 and 8 mg/d) were compared with those of bovine somatotropin (bST; 4 and 8 mg/d) in finishing lambs. Measures of comparison included growth performance, carcass composition, and growth-related clinical chemistry traits. Although feed efficiency during the first 3 wk of treatment with bPL was improved by 14% (P < .05), feed efficiency for the full 6-wk treatment period did not differ from that of control lambs. Responsiveness to bPL may have been attenuated by high titer antibodies present after 2 wk of treatment. However, bPL also did not influence growth-related clinical chemistry traits during short-term (7 d) treatment, strongly suggesting that bPL was ineffective in finishing lambs at the doses tested. In contrast, bST improved 6-wk feed efficiency by an average of 17% (P < .05) and decreased feed intake by an average of 12% (P < .05). In addition, measures of carcass composition including longissimus muscle area, specific gravity of the rack, kidney and pelvic fat, and fat thickness demonstrated that bST, but not bPL, treatment decreased carcass fatness and increased carcass leanness. Treatment with bST, but not with bPL, affected IGF-I, insulin, glucose, and urea nitrogen in a dose-related manner. Thus, daily injections of bPL did not affect either performance or carcass quality, whereas performance and carcass responses of finishing lambs to bST were consistent with those reported by others.
- Byatt, J. C., Eppard, P. J., Munyakazi, L., Sorbet, R. H., Veenhuizen, J. J., Curran, D. F., & Collier, R. J. (1992). Stimulation of milk yield and feed intake by bovine placental lactogen in the dairy cow.. Journal of dairy science, 75(5), 1216-1223.More infoPMID: 1597576;Abstract: A 6 x 6 Latin square design was used to test the effects of recombinant bovine placental lactogen on milk yield, milk composition, feed intake, and blood hormone and metabolite levels in nonpregnant lactating cows. The six treatments (5, 10, 20, and 40 mg/d of placental lactogen, water as negative control, and 20 mg/d of bST as positive control) were administered by subcutaneous injection twice daily for 9 d. Blood samples were taken during the last 5 d of the treatment period. The three highest doses of placental lactogen increased milk yield, and there was a linear dose effect, although placental lactogen was less potent than bST. Milk concentrations of lactose, protein, and fat were not altered by any of the treatments. Dry matter intake was increased by two of the doses of placental lactogen, but not by bST. Blood urea N concentration was decreased in a dose-dependent manner by placental lactogen and was also decreased by bST. Similarly, serum insulin-like growth factor-I was increased in a dose-dependent manner by placental lactogen and was also increased by bST. Plasma concentrations of NEFA and glucose were increased by bST, but placental lactogen had little or no effect on either of these parameters. Thus, placental lactogen appears to act, in part, as a weak somatotropin agonist; however, it also appears to have specific activities, e.g., stimulating feed intake.
- Byatt, J. C., Eppard, P. J., Veenhuizen, J. J., Sorbet, R. H., Buonomo, F. C., Curran, D. F., & Collier, R. J. (1992). Serum half-life and in-vivo actions of recombinant bovine placental lactogen in the dairy cow. Journal of Endocrinology, 132(2), 185-193.More infoPMID: 1541918;Abstract: The clearance rate of recombinant bovine placental lactogen (rbPL) from the blood serum of four lactating dairy cows was measured using a specific radio-immunoassay. Two animals were non-pregnant, while the other two were at approximately 120 days of gestation. The rbPL was administered as an i.v. bolus injection (4 mg total) via an indwelling jugular catheter. Blood samples were taken periodically for 180 min and assayed for rbPL. Analysis of the clearance curves for the bolus injection suggested a single-compartment model and a serum half-life of 7.25 min. In a second experiment with the same animals, following cessation of lactation, rbPL or bovine GH (bGH) were administered by s.c. injection (50 mg/day) for 5 consecutive days. Blood samples were taken twice per day during the treatment period and a 3-day pretreatment period. Samples were analysed for glucose, blood urea nitrogen (BUN), non-esterified fatty acids (NEFA), creatinine, insulin, insulin-like growth factor-I (IGF-II, tri-iodothyronine (T3), progesterone and IGF-binding protein-2 (IGFBP-2) to determine whether rbPL mediates similar metabolic effects to those of bGH. Administration of bGH stimulated an increse in NEFA, glucose, T3 and insulin, whereas none of these variables was affected by rbPL. The plasma concentrations of IGF-I and IGF-II were both increased by treatment with rbPL but, to a lesser extent than occurred with bGH. Interestingly, BUN and IGFBP-2 concentrations were reduced equally by bGH and rbPL. These results suggest that rbPL does not necessarily act as a GH agonist but, rather, may have distinct effect on intermediary metabolism that could be mediated through another specific receptor.
- Byatt, J. C., Warren, W. C., Eppard, P. J., Staten, N. R., Krivi, G. G., & Collier, R. J. (1992). Ruminant placental lactogens: structure and biology.. Journal of animal science, 70(9), 2911-2923.More infoPMID: 1399907;Abstract: Ruminant placental lactogens (PL) are members of the somatotropin, prolactin gene family that are synthesized by trophectodermal binucleate cells. The structure and biology of PL has been studied in the cow, sheep, and goat. Ruminant PL have greater structural identity to prolactin than somatotropin, although they bind to both lactogenic and somatogenic receptors. The molecular weights of ovine and caprine PL are approximately 23,000, whereas bovine PL is larger (31,000 to 34,000) due to glycosylation. Placental lactogen is secreted into both the fetal and maternal circulations. The concentration of PL in the fetus decreases with advancing gestation, whereas PL concentration peaks in the maternal circulation during the last third of pregnancy then reaches a plateau. Furthermore, the maternal concentration of PL is 100- to 1,000-fold higher in sheep and goats than in cows. The precise factors that modulate secretion of PL are unknown, although placental mass and nutrition seem to play a role. Ruminant PL have both lactogenic and somatogenic biological activities and may also have unique activities mediated through a specific receptor. There is circumstantial evidence to suggest that PL plays a role in stimulating mammogenesis. Placental lactogen secreted into the fetal compartment may also help regulate fetal growth. Direct experimental data indicate that PL can regulate maternal intermediary metabolism. Thus, it may act as a partitioning agent to regulate nutrient supply for fetal growth. The precise biological function of PL in ruminants, therefore, still needs to be defined.
- Collier, R. J., Vicini, J. L., Knight, C. D., McLaughlin, C. L., & Baile, C. A. (1992). Impact of somatotropins on nutrient requirements in domestic animals. Journal of Nutrition, 122(3 SUPPL.), 855-860.More infoPMID: 1542058;Abstract: Somatotropins increase nitrogen retention, decrease carcass fat and increase lean/fat ratio in growing ruminants and swine. However, responses are much more variable in growing ruminants. Maintenance requirements in both ruminants and swine are increased slightly with somatotropin treatment in conjunction with increased lean mass. This is associated with increases in partial efficiency of protein accretion, resulting in increased efficiency of growth. Additional information is required to accurately assess effects of somatotropin on nutrient requirements for growing ruminants and swine. Future studies should target degradable and nondegradable protein requirements for growing ruminants and the impact of somatotropin on these requirements; definition of dose, pattern and formulation of somatotropin for both ruminants and swine and interaction of somatotropin with other factors affecting feed intake in swine and ruminants.
- Eppard, P. J., Rogan, G. J., Boysen, B. G., Miller, M. A., Hintz, R. L., Hammond, B. G., Torkelson, A. R., Collier, R. J., & Lanza, G. M. (1992). Effect of high doses of a sustained-release bovine somatotropin on antibody formation in dairy cows.. Journal of dairy science, 75(11), 2959-2967.More infoPMID: 1460127;Abstract: Eighty-two lactating Holstein cows received either one, three, or five concurrent, intramuscular injections of a unit dose (.6 g) of zinc methionyl bST (some-tribove) or five doses of the vehicle. Injections were administered at 14-d intervals from 60 d postpartum until the end of lactation or necropsy. Thirty-eight cows continued on the same treatment for a 2nd yr. Blood bST antibodies developed within the first 7 wk of treatment, and the number of cows with anti-bST binding generally declined with time. Thirteen out of 59 cows receiving bST developed binding activity > 25% (positives) during the 1st yr. At the .6-g dose level, no binding was detected after wk 15. Seven of the 13 positive cows were among the group randomly selected to continue on study during yr 2. In the 2nd yr, only 2 out of 24 bST-treated cows were positive. Binding activity was associated with the IgG fraction in serum. Binding capacities of antibodies ranged from .625 to 3.04 mg of bST/L, and affinities ranged from 1.14 x 10(8) to 3.14 x 10(8) L/mol. Cows considered to be clinically positive had performance similar to those of their herdmates having binding < 25%. No evidence of a pathologic effect of antibodies existed in treated cows, their calves, or fetuses. The presence of anti-bST antibodies did not affect milk production of the cow or growth of the calves conceived during bST treatment.
- Peri, I., Shamay, A., McGrath, M. F., Collier, R. J., & Gertler, A. (1992). Comparative mitogenic and galactopoietic effects of IGF-I, IGF-II and DES-3-IGF-I in bovine mammary gland in vitro. Cell Biology International Reports, 16(4), 359-368.More infoPMID: 1525835;Abstract: Insulin-like growth factors (IGFs) I and II (IGF-I, IGF-II) and Des-3-IGF-I at physiological concentrations are potent mitogens of bovine undifferentiated mammary epithelial cells cultured in collagen in a serum-free medium. Des-3-IGF-I was found to be as potent as IGF-I, while IGF-II was significantly less active. All three factors acted either synergistically or additively with epidermal growth factor (EGF), cholera toxin and fetal calf serum (FCS). Indirect evidence indicates that despite its lower mitogenic activity the action of IGF-II is mediated through IGF-I receptors. The galactopoietic activity of Des-3-IGF-I and IGF-II was studied in an organ culture of bovine lactating mammary glands using lactogen-responsive fat synthesis as a test. Neither Des-3-IGF-I nor IGF-II exhibited galactopoietic activity nor did they affect the galactopoietic activity of prolactin. © 1992 Academic Press Ltd.
- Shimamoto, G. T., Byatt, J. C., Jennings, M. G., Comens-Keller, P., & Collier, R. J. (1992). Destripeptide insulin-like growth factor-I in milk from bovine somatotropin-treated cows. Pediatric Research, 32(3), 296-300.More infoPMID: 1408465;Abstract: Total somatomedins from milk of bovine somatotropin-treated cows were isolated and characterized to determine the relative amount of the three amino acid N-terminally truncated form of IGF-I (destripeptide IGF-I). The somatomedin fraction was isolated using organic solvent and solid-phase extractions followed by preparative reverse phase HPLC and affinity chromatography. The overall yield of IGF-I was 28%, and destripeptide IGF-I was recovered with similar efficiency. The isolated somatomedins were resolved by capillary zonal electrophoresis and identified using recombinant somatomedin standards. The concentration of destripeptide IGF-I relative to full length IGF-I was determined by amino terminal sequencing and by bioassay. Results from these experiments indicated that the level of destripeptide IGF-I in milk from somatotropin-treated cows was less than 3% of the IGF-I concentration. Destripeptide IGF-I is therefore a minor component of the somatomedins present in milk from treated cows and does not contribute significantly to the proliferative activity of this milk.
- Badinga, L., Collier, R. J., Thatcher, W. W., Wilcox, C. J., Head, H. H., & Bazer, F. W. (1991). Ontogeny of hepatic bovine growth hormone receptors in cattle.. Journal of animal science, 69(5), 1925-1934.More infoPMID: 2066302;Abstract: A series of studies examined the binding characteristics and ontogeny of hepatic growth hormone binding sites in dairy bulls on d 2, 30, 180, and 365 of age. Binding of iodinated recombinant bovine growth hormone ([125I]rbGH) to liver membrane receptors was membrane protein-dependent. Receptors were considered growth hormone-specific, because physiological concentrations of bovine prolactin (bPRL) failed to displace [125I]rbGH from bovine hepatocyte membranes. Only 50% of [125I]rbGH was bound reversibly to hepatic microsomes. Addition of dithiothreitol (DTT) to the receptor-assay buffer increased the binding of [125I]rbGH to hepatic membranes in a time-dependent manner. Moderate concentrations of Ca++ and Mg++ in the receptor-assay buffer had no detectable effects on binding of [125I]rbGH to hepatic microsomes. In growing dairy bulls, specific binding of [125I]rbGH per milligram of membrane protein increased from 1.9 +/- 1.8% at d 2 to 14.1 +/- 1.8% at d 180 and then declined to 5.2 +/- 1.6% at d 365. Likewise, concentration of insulin-like growth factor (IGF)-I in serum was low during the 1st mo of age (d 2, 13.3 +/- 8.8 ng/ml; d 30, 9.7 +/- 8.8 ng/ml), but it became maximal at d 180 (151.0 +/- 8.8 ng/ml). Circulating concentrations of IGF-II increased linearly during the 1st yr of growth. Serum concentrations of GH, triiodothyronine, and thyroxine declined from 39.9 +/- 6.5, 2.7 +/- .2, and 75.4 +/- 4.6 ng/ml at d 2 to 16.5 +/- 6.5, 1.3 +/- .2, and 53.4 +/- 4.6 ng/ml at d 30, respectively, and remained low through 1 yr of age. Insulin concentration in serum did not change significantly with development. Results indicated that increasing concentrations of specific bGH receptors in the bovine liver may play a key role in regulating postnatal growth in cattle.
- Byatt, J. C., Staten, N. R., Schmuke, J. J., Buonomo, F. C., Galosy, S. S., Curran, D. F., Krivi, G. G., & Collier, R. J. (1991). Stimulation of body weight gain of the mature female rat by bovine GH and bovine placental lactogen. Journal of Endocrinology, 130(1), 11-19.More infoPMID: 1880472;Abstract: Mature female rats (200 g) were treated for 10 days with either recombinant bovine GH (bGH) or recombinant bovine placental lactogen (bPL) to compare the somatogenic responses elicited by these hormones. The treatments were administered by daily s.c. injection at four dose levels (0.19, 0.56, l.67 and 5.0 mg/day). Both bGH and bPL stimulated significant increases in weight gain, but the slopes of the dose-response curves were different (P < 0.05). Bovine PL was more potent than bGH (P < 0.01) at the lowest dose, although there were no differences between treatment groups at the three higher doses. Feed consumption was stimulated more by bPL than bGH at all doses (P < 0.001). The concentration of insulin-like growth factor-I (IGF-I) in blood plasma was increased by bGH in a dose-responsive manner and was higher than control at doses of l.67 and 5 mg/day (P < 0.05). Fow doses of bPL stimulated increases in IGF-I similar to those with bGH. At the highest dose of bPL, however, there was no concomitant increase in plasma IGF-I. Nevertheless, the growth rate of the animals in this group matched that of the group given the highest dose of bGH. Receptor binding studies indicated that bPL bound to both GH and prolactin receptors. This is consistent with the growth data which suggest that bPL stimulated weight gain through a somatogenic mechanism as well as by another route, possibly mediated by lactogenic receptors.
- Cole, W. J., Madsen, K. S., Hintz, R. L., & Collier, R. L. (1991). Effect of recombinantly-derived bovine somatotropin on reproductive performance of dairy cattle. Theriogenology, 36(4), 573-595.More infoAbstract: Data from 814 cows involved in five separate full lactation studies were used to assess the effect of recombinantly-derived methionyl bovine somatotropin (sometribove) on reproductive performance. Data were separated by parity (first and second or greater), route of administration (intramuscular: i.m. or subcutaneous: s.c.), length of breeding period (number of days in milk), and level of production (high vs low). Through 305 days in milk, pregnancy rates were reduced 18% in primiparous, sometribove-treated (i.m.) cows but were not significantly affected in multiparous cows. No differences were noted in either parity group when sometribove was administered subcutaneously. The level of production was more often found to be a significant factor affecting reproductive parameters than was sometribove administration. In general, length of the breeding period and level of milk production had a greater influence on reproductive performance than treatment with sometribove. © 1991.
- Collier, R. J., Miller, M. A., Hildebrandt, J. R., Torkelson, A. R., White, T. C., Madsen, K. S., Vicini, J. L., Eppard, P. J., & Lanza, G. M. (1991). Factors affecting insulin-like growth factor-I concentration in bovine milk.. Journal of dairy science, 74(9), 2905-2911.More infoPMID: 1779049;Abstract: To establish the naturally occurring range of insulin-like growth factor-I concentrations in bovine milk, samples from individual cows (n = 409) managed on five Missouri dairy herds were assayed. Parity, stage of lactation, and farm affected milk insulin-like growth factor-I concentration. Milk insulin-like growth factor-I concentration was higher in early lactation than mid and late lactation with concentrations in multiparous cows exceeding those in primiparous cows. Insulin-like growth factor-I concentration was negatively correlated to milk production the day of sample collection (r = -.15) and not correlated to predicted 305-d milk yields. Unprocessed bulk tank milk samples (n = 100) from a commercial processing plant had a mean concentration of insulin-like growth factor-I in milk of 4.32 ng/ml with a range of 1.27 to 8.10 ng/ml. This distribution was similar to the range detected in samples from individual cows, but values were lower than those reported for human milk. Concentration of insulin-like growth factor-I in milk was not altered by pasteurization (at 79 degrees C for 45 s). However, insulin-like growth factor-I was undetectable in milk heated to temperatures (121 degrees C for 5 min) required for infant formula preparation or in commercially available infant formula. These data indicated that insulin-like growth factor-I is a normal but quantitatively variable component of bovine milk that is not destroyed by pasteurization but is undetectable in infant formula. Concentration of insulin-like growth factor-I in bovine milk is lower than concentrations reported for human milk yet similar to those reported for human saliva.(ABSTRACT TRUNCATED AT 250 WORDS)
- Eppard, P. J., Hudson, S., Cole, W. J., Hintz, R. L., Hartnell, G. F., Hunter, T. W., Metzger, L. E., Torkelson, A. R., Hammond, B. G., & Collier, R. J. (1991). Response of dairy cows to high doses of a sustained-release bovine somatotropin administered during two lactations. 1. Production response.. Journal of dairy science, 74(11), 3807-3821.More infoPMID: 1757623;Abstract: This study evaluated the effect of sometribove (zinc methionyl bST) in a sustained-release formulation administered to lactating cows at concentrations up to 3.0 g every 14 d over two lactations. Eighty-two lactating Holstein cows in their first, second, or third lactation were assigned to the study. Cows received .6, 1.8, or 3.0 g of bST in one, three, or five intramuscular injections of a unit dose (.6 g) every 2 wk. Controls received five injections of the vehicle (equivalent volume to the 3.0-g treatment) every 2 wk. Injections were administered from 60 +/- 3 d postpartum until dry-off or necropsy. Thirty-eight animals were continued on treatment for a second consecutive lactation. During the 1st yr of treatment, bST increased mean 3.5% FCM by 7.2, 9.4, and 8.4 kg/d over control production (21.1 kg/d). During the 2nd yr, milk response to .6, 1.8, and 3.0 g of bST averaged 10.6, 3.6, and 4.9 kg/d over controls (24.8 kg/d). The incidence of clinical mastitis increased in the 3.0-g group relative to controls during the 2nd yr. Thus, salable FCM averaged 8.1, 9.1, and 6.2 kg/d above controls (yr 1) and 12.1, 4.7, and -2.8 kg/d (yr 2) for the .6-, 1.8-, and 3.0-g groups. Salable FCM was unaffected by mastitis at a proposed commercial dose (.6 g). Milk fat, protein, lactose, calcium, phosphorus, zinc, magnesium, and ash concentrations were unaffected by bST treatment. Calculated energy, calcium, phosphorus, and protein balances also were unaffected except for early decreases of up to 5 Mcal/d, and 40, 20, and 600 g/d, respectively, until feed intake increased. Milk serum bST concentrations greater than the assay limit of sensitivity (1 ng/ml) were routinely measurable only at doses of 1.8 and 3.0 g. Results confirmed that bST concentrations in milk serum are exceedingly small. Overall, supraphysiological doses of sometribove increased milk production with little effect on composition. No toxic effects of bST were observed.
- Johnson, H. D., Li, R., Manalu, W., Spencer-Johnson, K., Becker, B. A., Collier, R. J., & Baile, C. A. (1991). Effects of somatotropin on milk yield and physiological responses during summer farm and hot laboratory conditions.. Journal of dairy science, 74(4), 1250-1262.More infoPMID: 1860972;Abstract: The effects of bST on performance and physiological responses of lactating cows was studied under farm summer and laboratory heat conditions. Twelve cows, 90 to 50 d postpartum, were injected with either bST or vehicle solution for 30 d under farm summer and 10 d under either laboratory thermoneutral or heat conditions. Somatotropin increased milk yield by 6.1 (21%), 8.1 (32%), and 7.3 kg (35%) under the farm summer, laboratory thermoneutral, and heat conditions, respectively. Somatotropin also increased milk fat by 15 and 19% and dry matter intake by 16 and 18% under laboratory thermoneutral and heat conditions, respectively. Somatotropin increased the efficiency of feed conversion into milk without any significant changes in body weight and temperatures. Somatotropin reduced plasma concentrations of triiodothyronine and cortisol and had no effect on plasma prolactin and insulin concentrations. Somatotropin did not increase water intake; however, hematocrit was decreased. The results suggest that stimulatory effects of bST on milk production are still observed on heat-stressed cows without any significant indications of additional heat stress.
- McGrath, M. F., Collier, R. J., Clemmons, D. R., Busby, W. H., Sweeny, C. A., & Krivi, G. G. (1991). The direct in vitro effect of insulin-like growth factors (IGFs) on normal bovine mammary cell proliferation and production of IGF binding proteins. Endocrinology, 129(2), 671-678.More infoPMID: 1713160;Abstract: Mammary epithelial cells isolated from pregnant, nonlactating heifers were grown in vitro using collagen substrates. Using these systems, the truncated form of insulin growth factor-1 (IGF-1) (des-3-IGF-1), IGF-1, and IGF-2 all stimulated a significant (0.5 to 1 fold) increase in cell proliferation (des-3-IGF-1 > IGF-1 > IGF-2). When grown in media containing serum plus IGF-1, normal bovine mammary cells also produced and secreted at least four species of IGF-binding protein (IGFBP) ranging from 21K to 48K (as demonstrated by ligand blot analysis). However, cells grown in serum free media secreted detectable quantities of only 2 major forms of IGFBP of 34K and 48K. Using immunoblot analysis, these proteins were identified as IGFBP-2 and IGFBP-3, respectively. Both proteins were inducible by the addition of IGF to the serum free media (relative potency; IGF-1 > des-3-IGF-1 > IGF-2). Using RIA analysis, bovine mammary cells cultured in the presence of IGF-1 produced 20-25 ng/ml IGFBP-2 compared to control cultures which secrete approximately 1.0 ng/ml. Cells exposed to des-3-IGF-1 produced 40-60% less IGFBP-2 whereas insulin and IGF-2 did not stimulate significant IGFBP-2 production. These data indicate that normal bovine mammary cells secrete IGFBP-2 and IGFBP-3. This secretion is stimulated by IGF-1 and des-3-IGF-1 suggesting a mechanism for regulating local IGF activity.
- McGuire, M. A., Beede, D. K., Collier, R. J., Buonomo, F. C., DeLorenzo, M. A., Wilcox, C. J., Huntington, G. B., & Reynolds, C. K. (1991). Effects of acute thermal stress and amount of feed intake on concentrations of somatotropin, insulin-like growth factor (IGF)-I and IGF-II, and thyroid hormones in plasma of lactating Holstein cows.. Journal of animal science, 69(5), 2050-2056.More infoPMID: 2066314;Abstract: Our objective was to evaluate effects of acute thermal stress, independent of reduced feed intake caused by elevated temperatures, and of reduced feed intake in thermal comfort on plasma concentrations of somatotropin, insulin-like growth factors I and II, thyroxine, and triiodothyronine. Six Holstein cows (averaging 475 +/- 18 kg BW, 2.3 +/- .3 parities, and 96 +/- 12 d in lactation) surgically fitted with catheters in the hepatic portal vein, mesenteric vein, and intercostalis posterior artery were exposed to treatments of thermal comfort environments with ad libitum or restricted (75% of ad libitum) DM intake and a thermal stress environment with ad libitum intake in two balanced 3 x 3 Latin squares. Thermal stress increased rectal temperatures and respiration rates. Dry matter intake of the thermal-stressed cows offered feed ad libitum (11.1 +/- .7 kg/d) was similar to the experimentally imposed reduction in DM intake of the thermal comfort restricted group (11.5 +/- .7 kg/d). Dry matter intake of cows in thermal comfort was 15.1 +/- .7 kg/d. Plasma somatotropin concentrations tended (P less than .08) to decrease during thermal stress but were unchanged by amount of feed intake in thermal comfort environments. Concentrations of IGF-I were not affected by treatments. Concentrations of IGF-II tended (P less than .14) to increase with thermal stress compared with thermal comfort treatments. Thyroxine concentrations tended (P less than .15) to increase in the thermal stress treatment compared with the thermal comfort restricted intake treatment. Triiodothyronine tended (P less than .11) to decrease with restriction in feed intake in the thermal comfort environment.(ABSTRACT TRUNCATED AT 250 WORDS)
- Vicini, J. L., Buonomo, F. C., Veenhuizen, J. J., Miller, M. A., Clemmons, D. R., & Collier, R. J. (1991). Nutrient balance and stage of lactation affect responses of insulin, insulin-like growth factors I and II, and insulin-like growth factor-binding protein 2 to somatotropin administration in dairy cows. Journal of Nutrition, 121(10), 1656-1664.More infoPMID: 1765832;Abstract: Six Holstein cows were used in a complete block design to examine effects of period of lactation and somatotropin (bST) administration on concentrations of insulin, insulin-like growth factors (IGF-I, IGF-II), and IGF-binding protein 2 (IGFBP-2). During late lactation, the dry period and the subsequent early lactation, cows received injections of NaHCO3 buffer for 5 d and bST for 7 d. Cows were in positive energy and protein balances during late lactation and the dry period and in slight negative balances during early lactation. Basal insulin concentrations were highest in late lactation (170 pmol/L), whereas bST concentrations were higher in early lactation (0.6 μg/L). Insulin was increased by bST in the dry period (255 pmol/L) and late lactation (149 pmol/L) but not in early lactation (14 pmol/L), probably because of greater availability of glucose during positive nutrient balance. Basal IGF-I was lowest in early lactation (63.6 μg/L) but was increased by bST during all periods. The IGF-I response to bST administration was lower during early lactation (74.1 μg/L) compared with late lactation (123.6 μg/L) and dry period (146.0 μg/L). The IGF-II concentrations were not affected by period of lactation of bST administration but IGF-II tended to be higher during bST administration when cows were dry. Concentration of IGFBP-2 was higher during early lactation when cows were in negative nutrient balance (479.5 μg/L) than during the dry period (289.2 μg/L) and was decreased with bST. These data support a role of insulin and IGF in regulation of milk production. Availability of nutrients may be involved in regulating these hormones, particularly during bST treatment.
- Becker, B. A., Johnson, H. D., Li, R., & Collier, R. J. (1990). Effect of farm and simulated laboratory cold environmental conditions on the performance and physiological responses of lactating dairy cows supplemented with bovine somatotropin (BST). International Journal of Biometeorology, 34(3), 151-156.More infoPMID: 2083980;Abstract: A study was conducted to evaluate the effect of bovine somatotropin (BST) supplementation in twelve lactating dairy cows maintained in cold environmental conditions. Six cows were injected daily with 25 mg of BST; the other six were injected with a control vehicle. Cows were maintained under standard dairy management during mid-winter for 30 days. Milk production was recorded twice daily, and blood samples were taken weekly. Animals were then transferred to environmentally controlled chambers and exposed to cycling thermoneutral (15° to 20° C) and cycling cold (-5° to +5° C) temperatures for 10 days in a split-reversal design. Milk production, feed and water intake, body weights and rectal temperatures were monitored. Blood samples were taken on days 1, 3, 5, 8 and 10 of each period and analyzed for plasma triiodothyronine (T3), thyroxine (T4), cortisol, insulin and prolactin. Under farm conditions, BST-treated cows produced 11% more milk than control-treated cows and in environmentally controlled chambers produced 17.4% more milk. No differences due to BST in feed or water intake, body weights or rectal temperatures were found under laboratory conditions. Plasma T3 and insulin increased due to BST treatment while no effect was found on cortisol, prolactin or T4. The results showed that the benefits of BST supplementation in lactating dairy cows were achieved under cold environmental conditions. © 1990 International Society of Biometeorology.
- Byatt, J. C., Larson, B. R., Baganoff, M. P., McGrath, M. F., & Collier, R. J. (1990). Purification and partial characterization of a bovine epidermal growth factor-like polupeptide. Biochemistry International, 20(6), 1179-1187.More infoPMID: 2369415;Abstract: A heterologous radioreceptor assay was developed to follow the purification of an EGF-like polypeptide from bovine kidney. Purification of the growth factor was facilitated by the use of a novel affinity column using fixed A431 cells attached to sephadex beads. The mol. wt. of the purified EGF-LP was estimated to be 5480 from the amino acid composition. The purified EGF-like polypeptide stimulated the proliferation of bovine mammary epithelial cells and appeared to be equipotent to mouse EGF. Available evidence suggests that the purified molecule is distinct from bovine TGF-alpha.
- Byatt, J. C., Schmuke, J. J., Comens, P. G., Johnson, D. A., & Collier, R. J. (1990). The effect of bovine lactoferrin on muscle growth in vivo and in vitro. Biochemical and Biophysical Research Communications, 173(2), 548-553.More infoPMID: 2260967;Abstract: Lactoferrin was found to be a potent stimulator of proliferation for L6 myoblasts. Both apo and holo-forms of lactoferrin were equipotent. By contrast, only the holo-form of transferrin (a structurally related iron binding protein) stimulated proliferation, apo-transferrin was without activity. Holo-transferrin was also less stimulatory than lactoferrin. Purified lactoferrin was administered to mature female rats and to neonatal rats by daily subcutaneous injection to determine if there was a measurable effect on muscle cell growth in vivo. Results from the in vivo studies suggest that lactoferrin has little or no effect on muscle cell growth in the whole animal. © 1990 Academic Press, Inc.
- Byatt, J. C., Welply, J. K., Leimgruber, R. M., & Collier, R. J. (1990). Characterization of glycosylated bovine placental lactogen and the effect of enzymatic deglycosylation on receptor binding and biological activity. Endocrinology, 127(3), 1041-1049.More infoPMID: 2167203;Abstract: Bovine placental lactogen (bPL) is a glycoprotein hormone that has both somatogenic and lactogenic properties. Purified preparations of the hormone contain many isoforms that are separated by isoelectric focusing. The sequence for bPL contains one consensus site for an N-linked oligosaccharide and many potential sites for O-linked sugars. To determine whether the isoforms are the result of differences in glycosylation, the oligosaccharide portion of bPL was partially characterized. In addition, a number of the isoforms were isolated and enzymatically deglycosylated to determine the effect of O- and N-linked glycosylation on biological activity. Biological activity was assessed in a somatotropin radioreceptor assay and also in the Nb2 lymphoma lactogenic bioassay. The structure of N-linked oligosaccharide was found to be sialylated and triantennary and appeared to be the same for all of the different charge isomers. Compositional analysis suggested that O-linked oligosaccharides were also present. Treatment of the intact hormone with neuraminidase resulted in the loss of some, but not all, of the isoforms, suggesting that a large degree of the charge heterogeneity is due to posttranslational modifications unrelated to glycosylation. Enzymatic removal of N-linked oligosaccharides from native bPL resulted in a 1.2-2.3-fold increase in binding to the somatotropin receptor, whereas receptor binding was unaffected by enzymatic removal of O-linked oligosaccharide. Lactogenic activity was affected very little by the removal of either type of oligosaccharide. The data suggests that glycosylation of bPL may have a small effect on receptor specificity, but that overall its presence does not dramatically affect receptor binding or biological activity.
- Hammond, B. G., Collier, R. J., Miller, M. A., McGrath, M., Hartzell, D. L., Kotts, C., & Vandaele, W. (1990). Food safety and pharmacokinetic studies which support a zero (0) meat and milk withdrawal time for use of sometribove in dairy cows.. Annales de Recherches Veterinaires, 21 Suppl 1, 107S-120S.More infoPMID: 2080839;Abstract: Sometribove (SB) is a synthetic form of bovine somatotropin (BST) whose amino acid sequence is the same for 190 of the 191 amino acids in BST. Administration of 500 mg of SB to dairy cows every 14 d increases the efficiency of milk production. Regulatory agencies have authorized a zero (0) milk and meat withdrawal time for investigational use of SB. The scientific basis for this authorization is as follows: 1) BST and other non-primate somatotropins are not active in humans, due to differences in the amino acid sequence from human somatotropin, which limits the ability of BST to bind to receptors on human tissues. 2) SB is not orally active, as it is degraded like other proteins when eaten. Administration of 50,000 microgram/kg/d SB to rats for 90 d produced no growth response. 3) Residual levels of SB in meat/milk are very low (ppb) and comparable to endogenous BST levels. 4) Residual levels (ppb) of insulin-like growth factor I (IGF-I) in meat and milk are only marginally increased by SB treatment (somatotropin stimulates local production of IGF-I in tissues to mediate some of its biological effects. 5) IGF-I was not orally active when fed to rats at doses ranging from 200 to 2,000 microgram/kg for 14 d.
- Hauser, S. D., McGrath, M. F., Collier, R. J., & Krivi, G. G. (1990). Cloning and in vivo expression of bovine growth hormone receptor mRNA. Molecular and Cellular Endocrinology, 72(3), 187-200.More infoPMID: 2289631;Abstract: A cDNA for the bovine growth hormone (bGH) receptor has been cloned out of a cDNA library prepared from liver of a pregnant Holstein heifer. The cDNA clone hybridizes to a single 4.5 kb mRNA species and shares a high degree of sequence homology with growth hormone receptors cloned from other species. Utilizing the bGH receptor cDNA as a probe, a relatively high level of bGH-receptor mRNA was detected in bovine liver. In comparison to liver values, lower concentrations of bGH-receptor mRNA were detected in bovine kidney, anterior pituitary, and mammary gland. Because specific binding sites for bGH have not been convincingly demonstrated in isolated cell membranes from whole bovine mammary tissue, mammary tissue from two pregnant heifers (separate experiments) was separated into fractions enriched for epithelium, stroma, and blood components. These fractions were then probed for growth hormone receptor mRNA using solution hybridization-nuclease protection assays performed on isolated RNA. The assay results indicated that a low level of bGH-receptor mRNA is relatively evenly distributed throughout the mammary tissues of the two cows studied. In contrast, experiments using a probe to bovine insulin-like growth factor-I (IGF-I) indicate that the IGF-I mRNA is localized in the stromal/blood component of the mammary gland. These data suggest a possible paracrine mechanism for bGH action in the mammary gland. © 1990.
- Vicini, J. L., Hudson, S., Cole, W. J., Miller, M. A., Eppard, P. J., White, T. C., & Collier, R. J. (1990). Effect of acute challenge with an extreme dose of somatotropin in a prolonged-release formulation on milk production and health of dairy cattle.. Journal of dairy science, 73(8), 2093-2102.More infoPMID: 2229598;Abstract: Eight pregnant Holstein cows were given weekly injections of 15 g of recombinant bST over a 2-wk period for a total dose of 30 g to determine signs of acute toxicity. Cows were monitored intensively throughout the study, and samples were taken for analyses of hormones, metabolites, chemistries, hematology, and urine analytes. Animal health throughout the study was generally excellent. Mean rectal temperatures were significantly higher in treated cows (38.7 vs. 39.2 degrees C). Least squares means for 3.5% FCM production were 15.9 and 23.0 kg/d, and net energy intakes were 29.4 and 26.9 Mcal/d for control and treated cows, respectively. Somatotropin concentrations reached more than 250 ng/ml on d 10 and remained above 200 ng/ml. Insulin and glucose concentrations were also increased but returned toward baseline values. Free fatty acid concentrations were higher in treated cows, but beta-hydroxybutyrate was not affected. Most hematological measurements were unaffected except for a reduction in erythrocyte number in treated cows and decreases in hematocrit and hemoglobin, but values were within clinically normal ranges. Although cows received in 2 wk a dose that was equivalent to the amount administered during more than 2 yr of continuous use, no signs of acute toxicity to bST were observed.
- McGuire, M. A., Beede, D. K., DeLorenzo, M. A., Wilcox, C. J., Huntington, G. B., Reynolds, C. K., & Collier, R. J. (1989). Effects of thermal stress and level of feed intake on portal plasma flow and net fluxes of metabolites in lactating Holstein cows.. Journal of animal science, 67(4), 1050-1060.More infoPMID: 2715110;Abstract: Six Holstein cows (averaging 475 kg body weight, 2.3 parities and 96 d in lactation) fitted with catheters in the hepatic portal vein, mesenteric vein and intercostalis posterior artery were exposed to treatments of thermal comfort environments with libitum or restricted (75% of ad libitum) DM intake and a thermal stress environment with ad libitum intake in two balanced 3 x 3 latin squares to evaluate effects of thermal stress on portal plasma flow and net fluxes of metabolites. Portal plasma flow was measured by administering a primed, continuous infusion of para-aminohippurate into a mesenteric vein and determining its concentration and dilution in portal vein plasma. Thermal stress treatment increased rectal temperatures and respiration rates. Dry matter intake decreased from thermal comfort ad libitum level (15.1 kg/d) to lower levels in thermal comfort restricted (11.5 kg/d) and thermal stress (11.1 kg/d) treatments. Portal plasma flow was related directly to level of DM intake, declining about 14% with thermal comfort restricted intake and thermal stress environment treatments compared with the thermal comfort restricted intake and thermal stress environment treatments compared with the thermal comfort ad libitum intake treatment. Net flux of alpha-amino N was reduced 20 and 35% by thermal comfort restricted intake and thermal stress treatments compared with the thermal comfort ad libitum intake treatment. Net fluxes of urea N, ammonia N and glucose were not affected by experimental treatments. A portion of the negative effects of thermal stress on milk production can be explained by decreased nutrient intake and decreased nutrient uptake by the portal-drained viscera of the cow.
- Davis, S. R., Collier, R. J., McNamara, J. P., Head, H. H., & Sussman, W. (1988). Effects of thyroxine and growth hormone treatment of dairy cows on milk yield, cardiac output and mammary blood flow.. Journal of animal science, 66(1), 70-79.More infoPMID: 3366719;Abstract: Four cows received thyroxine injections (T4; 20 mg/d) and three cows received growth hormone injections (GH; 44 mg/d) for 4 d during successive 16-d experimental periods. Measurement was made of milk yield, protein yield, mammary tyrosine and phenylalanine uptake, blood plasma hormone concentrations, mammary blood flow and cardiac output. Milk yield increased by 25% with T4 and 21% with GH treatment. Milk protein content tended to decline during T4 treatment and increase following GH treatment. Cardiac output increased by 8.9 liter/min (20%) and 4.6 liter/min (10%) with T4 and GH injection. Mammary blood flow (half-udder) increased from 3.6 to 4.9 liter/min (35%) and from 3.3 to 4.4 liter/min (33%) with T4 and GH treatment, respectively. These increases calculated on a whole-udder basis, accounted for 28% (T4) and 48% (GH) of the increases in cardiac output. The proportion of cardiac output perfusing the (whole) udder increased to 19.1% (T4) and 18.7% (GH), increases of 17 and 30%, respectively. Heart rate increased with T4 (but not GH treatment) from 80 to 115/min. Ratio of blood flow to milk yield was not changed by either treatment. The proportion of cardiac output perfusing the udder likely plays a major role in facilitating the partitioning of nutrients for milk synthesis.
- Davis, S. R., Collier, R. J., McNamara, J. P., Head, H. H., Croom, W. J., & Wilcox, C. J. (1988). Effects of thyroxine and growth hormone treatment of dairy cows on mammary uptake of glucose, oxygen and other milk fat precursors.. Journal of animal science, 66(1), 80-89.More infoPMID: 3366720;Abstract: Four cows received thyroxine injections (T4; 20 mg/d) and three cows received growth hormone injections (GH, 44 mg/d) for 4 d during successive 16-d experimental periods. Milk fat, lactose output, mammary uptake of glucose, oxygen and milk fat precursors were determined with each treatment. Injection of T4 increased lactose yield by 25% and fat yield 42%. The injection of GH increased fat and lactose yields by 24%. Both GH and T4 increased mammary glucose uptake by 35% and 45%, respectively, while T4 administration was associated with an increase in plasma glucose concentration from 67 to 84%. Thyroxine, but not GH, increased the ratio of mammary glucose uptake to lactose output from 1.24 to 1.58. Blood plasma acetate concentration declined following GH and T4 treatment by 17%. Mammary acetate uptake increased in response to GH injection in two of three cows but did not change with T4 injection. The injection of GH had no effect on plasma propionate concentration or mammary uptake. Thyroxine reduced plasma propionate content and mammary uptake. Neither T4 nor GH changed plasma free fatty acid concentration or mammary uptake. Thyroxine had no effect on plasma triglyceride concentration or mammary uptake, whereas GH increased mammary triglyceride uptake to the end of the experimental period. Mammary oxygen uptake was increased by GH as milk production increased. Increased mammary oxygen uptake following T4 treatment was transient. Change in mammary metabolism with T4 treatment permitted increased milk output without change in mammary oxygen consumption. Such a change may involve increased mammary utilization of pre-formed long-chain fatty acid and increased metabolism of glucose via glycolysis.
- Dehoff, M. H., Elgin, R. G., Collier, R. J., & Clemmons, D. R. (1988). Both type I and II insulin-like growth factor receptor binding increase during lactogenesis in bovine mammary tissue. Endocrinology, 122(6), 2412-2417.More infoPMID: 2967174;Abstract: Bovine GH is a potent stimulant of lactation, and the insulin-like growth factors I and II (IGF-I and -II) are believed to mediate GH's growth-promoting actions. Since all of IGF's known actions are mediated through its receptor subtypes, we analyzed the distribution of IGF receptor subtypes in lactating and nonlactating bovine mammary tissue. Analysis of competition curves showed that IGF-I had greater potency than IGF-II in competing with [125I]IGF-I for binding to membranes prepared from both lactating and nonlactating animals. An insulin concentration of 4 μg/ml displaced less than 40% of the [125I]IGF-I bound to membranes prepared from both lactating and nonlactating animals, indicating that a high percentage of [125I]IGF-I was bound to the type II receptor. Lactation was associated with an increase in the total amount of [125I]IGF-I bound, and this change was due to an increase in binding to both receptor subtypes. Specifically, membranes prepared from lactating animals had a 3-fold increase in binding competed for by insulin and a 2-fold increase in binding not competed for by insulin. Affinity cross-linking of [125I]IGF-I to membranes prepared from both lactating and nonlactating animals, followed by polyacrylamide gel electrophoresis (PAGE) and autoradiography, showed that 260K and 135K bands were present. Competition experiments indicated that unlabeled IGF-I effectively competed for binding to the 260K band, whereas insulin did not. Binding to the 135K band could be inhibited by both IGF-I and insulin. The intensity of the labeled bands showed that type II receptors were relatively more abundant than type I receptors in membranes from both lactating and nonlactating animals. Membranes prepared from lactating animals showed both 135K and 127K species of the type I receptor, whereas nonlactating animals showed only the 135K band. We conclude that type I and II receptors are present in bovine mammary tissue, and type II predominate. Lactation is associated with increases in the concentration of both receptor subtypes, especially type I receptors. Lactation may be associated with structural changes in the type I receptor. These changes in receptor distribution could play a role in modulating the physiological effects of the IGFs on mammary tissue.
- Morse, D., DeLorenzo, M. A., Wilcox, C. J., Collier, R. J., Natzke, R. P., & Bray, D. R. (1988). Climatic effects on occurrence of clinical mastitis.. Journal of dairy science, 71(3), 848-853.More infoPMID: 3372825;Abstract: Clinical mastitis records for 6.5 yr from a large north Florida dairy and corresponding daily weather data were analyzed. Monthly incidence of clinical mastitis was expressed as percent of cow-days in milk and graphed against monthly average daily maximum temperature humidity index values and monthly total rainfall. No trends were evident with rainfall. In 3 of 6 yr, monthly incidence of clinical mastitis increased more than 50% above annual incidence, and this followed high monthly temperature-humidity values. Least squares was used to estimate regression coefficients of temperature-humidity index categories based on 999,969 Holstein records. A temperature humidity index category represented the number of days used to calculate average daily maximum temperature-humidity index value. Sources of variation in observed occurrence of clinical mastitis were cow, parity, month, year, interaction of parity by month, and continuous effects of temperature-humidity index categories 2, 6, 15, 30, 60, each to third order and 60 by parity interaction. In all temperature-humidity index categories as the temperature-humidity index value increased, occurrence of clinical mastitis increased. When values rose from 55 to 80, twice as many for 2 d cows showed signs of clinical mastitis.
- Sharma, A. K., Rodriguez, L. A., Wilcox, C. J., Collier, R. J., Bachman, K. C., & Martin, F. G. (1988). Interactions of climatic factors affecting milk yield and composition.. Journal of dairy science, 71(3), 819-825.More infoPMID: 3372822;Abstract: Objectives were to evaluate effects of interactions of maximum temperature, minimum relative humidity, and solar radiation on milk yield and constituent traits. Effects of climate variables and their interactions were significant but small in most cases. Second order regression models were developed for several variables. Six were examined in detail: Holstein and Jersey milk yields, Holstein fat and Feulgen-DNA reflectance percent, and Jersey protein percent and yield. Maximum temperature had greatest influence on each response, followed by minimum relative humidity and solar radiation. Optimum conditions for milk production were at maximum temperatures below 19.4 degrees C, increasing solar radiation, and minimum relative humidity between 33.4 and 78.2% (cool sunny days, moderate humidity). Maximum Holstein fat percent of 3.5% was predicted for maximum temperatures below 30.8 degrees C, minimum relative humidity below 89%, and solar radiation below 109 Langleys; actual mean Holstein fat percent was 3.35%. Optimum climatic conditions for Jersey protein percent were at maximum temperature of 10.6 degrees C with solar radiation at 300 Langleys and relative humidity at 16% (cool sunny days, low humidity). Because noteworthy interactions existed between climate effects, response surface methodology was suitable for determining optimum climatic conditions for milk production.
- Badinga, L., Collier, R. J., Thatcher, W. W., Quintana, S. J., & Bazer, F. W. (1987). Covalent coupling of bovine growth hormone to its receptor in bovine liver membranes. Molecular and Cellular Endocrinology, 52(1-2), 85-89.More infoPMID: 3622922;Abstract: The structure of bovine somatotropin receptor was examined following covalent coupling of iodinated recombinant bovine growth hormone ([125I]rbGH) to bovine liver membrane receptors using ethylene glycol bis(succinimidyl succinate). Iodinated rbGH was incorporated into a complex of estimated Mr of 140000 under reducing conditions. Excess unlabeled rbGH, but not bovine prolactin (bPRL), inhibited completely the incorporation of [125I]rbGH into the Mr = 140000 species. In dairy bulls, the Mr = 140000 complex was undetectable soon after birth but became predominant at 6 months of age. No evidence was found to support presence of bPRL receptors in steer liver membranes. Assuming a 1:1 stoichiometry of hormone binding to receptor, it appears that bGH binds to a major receptor subunit of Mr = 119000 which does not recognize bPRL. © 1987.
- Byatt, J. C., Wallace, C. R., Bremel, R. D., Collier, R. J., & Bolt, D. J. (1987). The concentration of bovine placental lactogen and the incidence of different forms in fetal cotyledons and in fetal serum. Domestic Animal Endocrinology, 4(4), 231-241.More infoPMID: 3507892;Abstract: The concentration of bovine placental lactogen (bPL) was determined in fetal placentomes, allantoic fluid, amniotic fluid, maternal and fetal plasma throughout pregnancy. In addition, chromatofocusing chromatography was used to separate the different forms of bPL found both in fetal serum and in placental homogenates in order to determine whether the different forms that have been reported to exist in the cotyledon are also found in the fetal circulation. Reproductive tracts were collected from cows between 109 and 247 days of pregnancy. The concentration of bPL in the fetal cotyledonary tissue was measured by both radioreceptor assay and radioimmunoassay, both assays showed that the concentration of bPL in the fetal portion of the placentomes remained constant throughout the period of pregnancy tested. The mass of the placenta increased approximately 10-fold during the period of study but the concentration of bPL in the maternal plasma was low (0.9±0.1 ng/ml) at all stages of pregnancy tested. The mean concentration of bPL (Mean ± S.E.M.) in amniotic and allantoic fluid was 0.4±0.1 and 1.2±0.2 ng/ml respectively. Fetal blood contained the highest concentrations of bPL, from 11.6 to 18.4 ng/ml, and the concentration tended to decrease with advancing gestation (slope = 0.07, P = 0.001). Several forms of bPL were found in the fetal circulation; however, a higher percentage of forms with more acidic isoelectric points were found in the fetal serum than in placental homogenates. These results suggest that either some forms of bPL are more stable or that the hormone isolated from placental tissue is not representative of the final secreted product. © 1987.
- Malven, P. V., Head, H. H., & Collier, R. J. (1987). Secretion and mammary gland uptake of prolactin in dairy cows during lactogenesis.. Journal of dairy science, 70(11), 2241-2253.More infoPMID: 3693630;Abstract: Mammary arteriovenous differences of prolactin concentration and net mammary uptake of prolactin from blood were quantified near parturition in 9 dairy cows. Six cows were milked once daily for at least 6 d before parturition, and prepartum lactogenesis occurred in 3 of 6 cows. Prepartum milking 2 or more d before parturition abruptly increased secretion of prolactin into blood, but milkings within 1 d before or after parturition did not increase prolactin secretion. Concentrations of prolactin in whole milk sampled over 8 d before parturition (64.5 ng/ml) were substantially greater than those occurring several days after parturition (19 ng/ml). Milk prolactin concentrations were unaffected by the successful induction of prepartum lactogenesis, which greatly increased prepartum yields of milk (2 to 8 kg/milking). Therefore, the alveolar lumenal content of prolactin was greatest in pregnant cows with prepartum lactogenesis. This enhanced content of intraalveolar prolactin before parturition was associated with an absence of mammary uptake of prolactin immediately prior to ejection of the prolactin-containing milk from the alveoli. However, prolactin uptake was quickly restored to about 2 micrograms/min per half udder shortly after milk ejection. During the prepartum period, an enhanced intraalveolar reservoir of 200 to 400 micrograms prolactin, due to induction of prepartum lactogenesis, appears to saturate temporarily all putative sites for uptake of prolactin from blood.
- DeHoff, M. H., Stoner, C. S., Bazer, F. W., Collier, R. J., Kraeling, R. R., & Buonomo, F. C. (1986). Temporal changes in steroids, prolactin and growth hormone in pregnant and pseudopregnant gilts during mammogenesis and lactogenesis. Domestic Animal Endocrinology, 3(2), 95-105.More infoAbstract: Estrogen, progesterone and prolactin are involved in control of mammary growth in all species studied to date. The primary hormonal change temporally related to mammary development in swine is the estrogen rise which begins on day 60 of pregnancy. However, hormonal regulation of mammary development in swine is poorly understood. Plasma was obtained at 15-day intervals (days 15-112) throughout pregnancy, day of parturition and day 4 of lactation to determine relationships between hormonal profiles and mammary development in swine. Fetal plasma was also obtained from day 60 until parturition. Additional gilts were made pseudopregnant and sampled on days 60, 90 and 112. Plasma samples were assayed for estrogens, progesterone, prolactin and growth hormone. Maternal profiles of estrone- and estradiol-sulfate, increased to 2.6 and 0.6 ng/ml, repectively on day 30 of pregnancy, with return to basal concentrations by day 45. Periparturient concentrations of estrone and estradiol did reach 13 and 2.6 ng/ml, respectively. Free estrogen concentrations (estrone and estradiol) did not change significantly at day 30, but were elevated to 6 and 0.7 pg/ml at parturition. Progesterone concentration fluctuated only slightly from a mean concentration of 25 ng/ml until the preparturient decline, resulting in concentrations of 150 ng/ml). With the exception of estrone, hormonal concentrations in estrogen-treated pseudopregnant gilts did not differ from pregnant counterparts, demonstrating that pseudopregnant gilts are an excellent in vivo model to study estrogen effects on mammary development in swine. © 1986.
- Donovan, G. A., Badinga, L., Collier, R. J., Wilcox, C. J., & Braun, R. K. (1986). Factors influencing passive transfer in dairy calves.. Journal of dairy science, 69(3), 754-759.More infoPMID: 3711407;Abstract: Records from 2105 calves born over 2 yr on a large dairy in a subtropical climate were examined to delineate factors that influence passive transfer of colostral immunoglobulins and the effect of passive transfer of immunoglobulin on calf mortality. Seasonal effects on immunoglobulin absorption were detected with highest serum total protein occurring in February and March. Lower total protein concentrations were associated with elevated environmental temperatures in the summer months. Maternal antibody was highest in calves from second parity cows; and dystocia appeared to decrease the amount of immunoglobulin absorbed by the neonatal calf. Calves that died of infectious disease during the first 14 wk of life had significantly lower serum total protein concentrations than those that lived. Heritability of serum protein concentration in calves was .02 +/- .03.
- Kensinger, R. S., Collier, R. J., & Bazer, F. W. (1986). Effect of number of conceptuses on maternal mammary development during pregnancy in the pig. Domestic Animal Endocrinology, 3(4), 237-245.More infoAbstract: An experiment was conducted to determine if manipulation of conceptus number could alter estrogen, progesterone or prolactin concentrations in gilts and thereby influence mammary development. Estradiol-valerate injections, oviduct ligation or no treatment were utilized to form three groups of gilts with zero (n=5), 4 to 7 (n=4), or 8 to 11 (n=4) conceptuses, respectively. Blood samples were taken throughout pregnancy, and at day 110 of gestation all gilts were slaughtered and total mastectomies were performed. Mammary glands were analyzed for wet weights, dry weights, RNA and DNA contents. Results indicated conceptuses stimulated mammary development since mammary glands from pseudopregnant gilts had only 22% as much DNA as mammae from pregnant gilts. However, mammary DNA was not different between gilts with 4 to 7 or 8 to 11 conceptuses. The relationship between conceptus number and mammary gland DNA in gilts was best described by the quadratic equation y = 577 + 583x - 38x2, where y = total mammary DNA (mg) and x = conceptus number. Significant positive among-animal and within-group correlations between estrogen-sulfate or estrone concentrations in blood and maternal mammary DNA content suggest that estrogens may be the primary conceptus-derived mammogenic hormone in gilts. © 1986.
- Kensinger, R. S., Collier, R. J., & Bazer, F. W. (1986). Ultrastructural changes in porcine mammary tissue during lactogenesis. Journal of Anatomy, VOL. 145, 49-59.More infoPMID: 3429308;PMCID: PMC1166491;Abstract: Ultrastructural changes occurring in porcine mammary tissue were characterised between Day 90 of pregnancy and Day 4 of lactation. Porcine mammary tissue on Day 90 of pregnancy was composed of alveoli which contained negligible to moderate amounts of secretion. Epithelial cells of these alveoli were relatively undifferentiated. The appearance and distribution of cellular organelles suggested that mammary epithelial differentiation had been initiated by Day 105 of pregnancy in the pig. A further increase in intracellular lipid droplets and granular endoplasmic reticulum suggested that differentiation had progressed by Day 112. On the day of parturition, secretions within the alveolar lumina assumed the appearance of normal milk (as opposed to colostrum) and the epithelia displayed a distinct cellular polarity characteristic of lactating mammary tissue. By Day 4 of lactation, differentiation of epithelial cells appeared to be complete, with dilated cisternae of the granular endoplasmic reticulum and with numerous secretory vesicles. Elongated microvilli were present and numerous cells contained lipid droplets which were being extruded into the lumina. Data from this and previous studies indicate that lactogenesis in the pig occurs in two stages. Stage 1 occurs between Days 90 and 105 of pregnancy, and Stage 2 between Day 112 of pregnancy and early lactation when the predominant feature is active milk secretion.
- Kensinger, R. S., Collier, R. J., Bazer, F. W., & Kraeling, R. R. (1986). Effect of number of conceptuses on maternal hormone concentrations in the pig.. Journal of animal science, 62(6), 1666-1674.More infoPMID: 3733561;Abstract: This study examined the effect of number of conceptuses on maternal concentrations and profiles of estrogen sulfate, estrone, estradiol-17 beta, progesterone and prolactin in gilts. Estradiol-valerate injections were used to induce pseudopregnancy (O conceptuses; n = 5) and oviduct ligation or no treatment were utilized to obtain pregnant gilts with 4 to 7 (n = 4), or 8 to 11 (n = 4) conceptuses, respectively. Blood samples were collected every 10 d from d 10 through 110 of pregnancy or pseudopregnancy. At 110 d after onset of estrus, all gilts were slaughtered and numbers and(or) weights of fetuses, corpora lutea, placentae and the empty uterus were determined. Concentrations of estrogen sulfate and estrone, but not progesterone or prolactin, were associated with fetal number, total fetal weight, total placental weight or empty uterine weight. In contrast, only progesterone was highly correlated with number of corpora lutea. Results suggest that most conjugated estrogen, estrone and estradiol were of fetal-placental origin, whereas little, if any, placental production of progesterone or prolactin occurred. Increases in estrogen sulfate and estrone concentrations were observed at gestation d 30 and from d 70 to 100. The latter increase coincides with previously established increases in the rate of maternal mammary development and fetal growth.
- Malven, P. V., Head, H. H., & Collier, R. J. (1986). Effect of dry period versus continuous milking on periparturient concentrations of bovine prolactin in milk from half udders.. Journal of dairy science, 69(6), 1523-1527.More infoPMID: 3745570;Abstract: Four multiparous cows were used to determine whether continuous twice daily milking of half the udder throughout the dry period would alter the prepartum accumulation of prolactin in secreted milk. The control half of each udder was allowed a dry period of 43 d, and twice daily milking was reinitiated in this half udder 11 d before parturition, whereas the treated half was milked continuously throughout. Milk from the treated half decreased to very low yields despite continuous milking, whereas concentrations of prolactin in milk remained low and without much day-to-day variation within each cow. Concentrations of prolactin in milk and yields of milk increased during the week before parturition in both halves of the udder, but there were no significant differences due to previous continuous milking. Therefore, prepartum accumulation of high concentrations of prolactin in secreted milk did not appear to depend on prior occurrence of a dry period. Elevated concentrations of prolactin in milk declined rapidly and equally in each half udder after parturition.
- Taylor, S. E., Buffington, D. E., Collier, R. J., & DeLorenzo, M. A. (1986). EVAPORATIVE COOLING FOR DAIRY COWS IN FLORIDA.. Paper - American Society of Agricultural Engineers.More infoAbstract: This research analyzes the potential benefits of using a pad and fan evaporative cooling system for dairy cattle located in Florida. The objectives of this research are to evaluate the effects on cow comfort and milk production resulting from an experiment using an evaporatively cooled structure and to predict milk production benefits (if any) for evaporatively cooled dairy cows in Florida during a typical year. Study materials, methods and results are discussed.
- Badinga, L., Collier, R. J., Thatcher, W. W., & Wilcox, C. J. (1985). Effects of climatic and management factors on conception rate of dairy cattle in subtropical environment.. Journal of dairy science, 68(1), 78-85.More infoPMID: 3980812;Abstract: Breeding records, representing 12,038 inseminations at Bassett's Dairy Farm (Monticello, FL), were analyzed to document effects of environmental and management factors on fertility of dairy cattle from January 1, 1975 to December 31, 1977. Conception rates of lactating cows decreased sharply when maximum air temperature on day after insemination exceeded 30 degrees C. In contrast, conception rates for heifers did not decline until 35 degrees C. Virgin heifers had higher conception rates for all services (50%) than lactating cows (34%) and suffered only slight depression of fertility during summer months. Heifers required 1.5 services per conception compared with 2.3 for lactating cows. Relationship between conception rate and rainfall on day after insemination was negative and curvilinear. Jerseys had higher conception rates (45%) than Holstein (39%) and Brown Swiss (41%). Services per conception were 1.7, 2.0, and 1.9. Substantial decreases of fertility were associated with advancing service number. Estrous status (standing; positive heat detection patch; mounting activity), inseminator, and year of service were related to variation of conception rate. Seasonal effects on fertility of lactating cows were marked. Thus, environmental management of the postpartum cow during hot summer months is warranted to maximize fertility.
- Badinga, L., Collier, R. J., Wilcox, C. J., & Thatcher, W. W. (1985). Interrelationships of milk yield, body weight, and reproductive performance.. Journal of dairy science, 68(7), 1828-1831.More infoPMID: 4031196;Abstract: Records (2263) from a single north Florida herd for 3 yr were evaluated in a series of analyses. Environment was subtropical. Data set included only cows that had normal milk records and became pregnant. Holsteins and Jerseys averaged 6799 and 4504 kg milk, 587 and 418 kg postpartum body weight, 164 and 141 days open, and 2.3 and 2.1 services per subsequent pregnancy. Pooled within breed, repeatabilities and heritabilities of these performance measures were .37, .15; .53, .25; .20, .06; and .30, 0. Estimable genetic correlations were milk yield and body weight -.09, milk yield and services per conception .38, and services per conception and body weight .37; range of standard errors was .22 to .39. Substantial genetic antagonism may exist between milk yield and body weight, and efficient reproduction. If results of this research are verified elsewhere, breeders should be aware that selection for increased weight could lead to decreased reproductive efficiency.
- Davis, S. R., & Collier, R. J. (1985). Mammary blood flow and regulation of substrate supply for milk synthesis.. Journal of dairy science, 68(4), 1041-1058.More infoPMID: 3889082;Abstract: In ruminants, mammary supply of substrate varies with rate of mammary blood flow and concentrations of blood substrates. Blood concentrations of most mammary substrates, except acetate and tryptophan, do not vary greatly with feed intake, short term. Fasting reduces mammary blood flow, whereas milking and injection of growth hormone or thyroxine increase flow. It is proposed that the fraction of cardiac output that perfuses the udder of lactating ruminants plays a role in regulation of nutrient partitioning between milk and body tissues. In fed animals this fraction is 15 to 16% of cardiac output, which declines on fasting to 8 to 9% and increases slightly following growth hormone treatment to 17.6%. Following realimentation of fasted cows or goats, mammary blood flow takes several hours to return to normal. Investigation of the mechanism of this response, in terms of the ability of the animal to recognize its nutritional status and partition nutrients accordingly, should prove fruitful to understanding causes of variations of milk production in response to feed quantity and quality. Several substrates show increased mammary arteriovenous difference with increasing blood concentrations. This may reflect differing ratios of blood flow:milk yield. The steep gradient of concentration of substrates across the mammary epithelial cell membrane suggests that a major impediment to substrate supply for milk synthesis is the rate of substrate transport across the membrane.
- Guilbault, L. A., Thatcher, W. W., Collier, R. J., & Wilcox, C. J. (1985). Periparturient endocrine changes of conceptus and maternal units in Holstein heifers bearing genetically different conceptuses.. Journal of animal science, 61(6), 1505-1515.More infoPMID: 4086400;Abstract: Holstein heifers (n = 21) were balanced across sires and assigned to three service-sire-breed groups in which heifers were inseminated artificially to either purebred Angus (n = 7), Holstein (n = 7) or Brahman (n = 7) bulls. Semen from four bulls was used for each service sire-breed group. Blood samples were collected from a jugular vein thrice weekly from d 160 to 265 of pregnancy, daily thereafter until 15 d postpartum, and then thrice weekly until d 60 postpartum. Concentrations of progesterone, estrone, estradiol, and estrone sulfate from 23 d prepartum to parturition, and of 15-keto-13,14-dihydro-prostaglandin F2 alpha (PGFM) from 2 d prepartum to d 15 postpartum were measured by radioimmunoassay. Heifers within the Brahman-service-sire group had longer gestations (P less than .05) than those of Holstein- or Angus-service-sire groups (285.0 vs 278.7), 279.0 d). Calf birth weight was lower (P less than .05) in Angus- than Holstein- and Brahman-service-sire groups (30.6 vs 36.1, 43.4 kg). Daily trends of prepartum maternal progesterone concentrations were approximately 1 ng/ml lower (P less than .01) in Angus- than Holstein- or Brahman-service-sire groups until luteolysis occurred. Heifers bearing crossbred Angus conceptuses had lower daily trends of prepartum estrogens concentrations (P less than .01), whereas heifers of the Holstein- and, even more dramatically, of the Brahman-service-sire groups had a higher magnitude and greater rise of plasma estrogens concentrations between d -10 and -1 prepartum (less than .01). Postpartum mean concentrations (P less than .05) and response curves of PGFM were lower (P less than .01) in the Angus- than in the Holstein- or Brahman-service-sire groups. Calf birth weights were correlated with least-squares means for maternal concentrations of prepartum estrone (r = .57), estradiol (r = .59) and estrone sulfate (r = .64) and postpartum maternal concentrations of PGFM (r = .56). Functional responses of the conceptus (e.g., estrogens) and maternal units (e.g., progesterone and PGFM) were influenced by conceptus genotype during the periparturient period.
- Guilbault, L. A., Thatcher, W. W., Collier, R. J., Wilcox, C. J., & Drost, M. (1985). Carry-over effects of periparturient endocrine changes on postpartum reproductive function of Holstein heifers bred to genetically different service sires.. Journal of animal science, 61(6), 1516-1526.More infoPMID: 4086401;Abstract: Effects of fetal sire on postpartum reproductive changes of the dam were studied in 21 Holstein heifers whose pregnancy had been initiated by either Angus (n = 7), Holstein (n = 7) or Brahman (n = 7) bulls. After parturition, all heifers were managed uniformly. Heifers in each service-sire-breed group were bled via jugular venipuncture thrice weekly from d 160 to 265 of pregnancy, daily thereafter until 15 d postpartum, and three times per week until d 60 postpartum. Ability of heifers to release prolactin (PRL) and luteinizing hormone (LH) was evaluated on d 10 postpartum after a simultaneous injection of thyrotropin releasing hormone (TRH; 100 micrograms) and gonadotropin releasing hormone (GnRH; 100 micrograms). Between d 5 and 60 postpartum, the reproductive tract of each heifer was examined rectally thrice weekly after collection of blood samples. Basal concentrations of LH from d 1 to 10 postpartum, as well as ability of the pituitary gland to release LH and PRL after the GnRH-TRH challenge, did not differ between service-sire-breed groups (P greater than .1). Means and profiles of progesterone concentrations during the first 60 d postpartum did not differ between service-sire-breed groups (P greater than .1). However, increases in progesterone concentrations following the GnRH-TRH challenge were synchronized more precisely in Angus (P less than .02) than in Holstein- and Brahman-service-sire groups. Daily rates of reduction in cervical and uterine horn diameters were higher (P less than .01) in Holstein- and Brahman- than in Angus-service-sire groups and were associated with higher profiles of postpartum 15-keto-13,14-dihydro-prostaglandin F2 alpha (PGFM) concentrations. Within-cow PGFM concentrations were correlated positively with cervical (r = .36) and uterine horn (r = .32) diameters. Postpartum ovarian responsiveness and uterine involution in Holstein heifers may be affected by genotypes of the conceptus they bore during pregnancy.
- Mallonée, P., Beede, D. K., Collier, R. J., & Wilcox, C. J. (1985). Production and physiological responses of dairy cows to varying dietary potassium during heat stress.. Journal of dairy science, 68(6), 1479-1487.More infoPMID: 4019886;Abstract: Objectives were to study influences of heat stress and dietary potassium content on production and physiological responses of 8 Jersey and 10 Holstein cows blocked by breed and assigned randomly to no shade or shade environments. Each cow received a different dietary potassium treatment (.66, 1.08, and 1.64% of dry matter) in each of three 30-day periods. Rates of potassium loss from skin were almost five times greater for no shade as for shade cows during the hottest part of the day (1300 to 1500 h). Overall, cows with no shade ate 56% less during the daytime (0800 to 1600 h), 19% more during nighttime (1600 to 0800 h), and 13% less total feed than cows with shade. Interactions of environment and breed with dietary potassium treatment suggest differences in feed intake and milk yield responses to increasing dietary potassium content. Total daily feed intake and milk yield of cows with no shade responded in curvilinear fashion to increasing dietary potassium, whereas responses in shade were small. Largest responses in no shade were as dietary potassium increased from .66 to 1.08%. Milk yield of Holsteins increased with increasing dietary potassium, but yield of Jerseys did not. Combined effects of elevated potassium loss from skin and reduced potassium and dry matter intake during heat stress suggested that lactating dairy cows may benefit from supplemental potassium.
- McNamara, J. P., Dehoff, M. H., Collier, R. J., & Bazer, F. W. (1985). Adipose tissue fatty acid metabolism during pregnancy in swine.. Journal of animal science, 61(2), 410-415.More infoPMID: 4044440;Abstract: In vitro adipose tissue fatty acid pool size (POOL), fatty acid release (FAR) and esterification (EST) were measured in peritoneal (PFP) and subcutaneous mammary (MFP) fat pads of swine at d 15, 30, 45, 60, 75, 90, 105 and 112 of pregnancy. Plasma free fatty acids (FFA) and triglycerides (TG) were not altered by stage of pregnancy. Basal EST in PFP was generally constant across pregnancy with a peak at d 75. Basal EST in MFP was elevated at d 30, 75 and 112. Esterification in response to norepinephrine stimulus (NE) was lower than basal rates in both fat depots. Basal FAR was constant throughout pregnancy in PFP, but elevated at d 75 and 90 in MFP. Fatty acid release in response to NE was biphasic with peaks at d 30 and in late pregnancy (in MFP, micromolar FAR in response to NE was 69.3% greater on d 75 to 112 than on d 45 to 60). Basal POOL was constant throughout pregnancy in both depots and lower than NE-stimulated POOL. All responses to NE were greater in MFP than in PFP, indicating that adipose tissue surrounding the developing mammary gland had higher metabolic activity and a greater response to NE than peritoneal adipose. Changes in fatty acid metabolism during pregnancy in swine are temporally related to published values for plasma steroids, fetal growth and mammary development. Metabolic adaptations in adipose and mannary epithelial tissue occur in synchrony with changing plasma estrogen concentrations, redirecting energy flow from maternal adipose tissue toward developing mammary and fetal tissue.
- Collier, R. J., McNamara, J. P., Wallace, C. R., & Dehoff, M. H. (1984). A review of endocrine regulation of metabolism during lactation.. Journal of animal science, 59(2), 498-510.More infoPMID: 6090379;Abstract: Lactogenesis signals the shift from uterine nutrient transfer to the fetus to neonatal nourishment at the mammary gland. Metabolic adaptations involved in this process are under endocrine regulation. Key events include an increase in blood flow to mammary tissue, a decrease in nutrient utilization by peripheral tissues and an increase in nutrient utilization by mammary tissue for milk synthesis. Deficits of certain substrates during early lactation require mobilization of those substrates from depot stores. Changes in metabolism of various tissues are related to changes in hormone receptor populations of those tissues and hormone concentrations in blood. Hormone receptors are therefore the primary mechanism by which information from the endocrine systems is linked to cellular metabolism. Endocrine changes at parturition result in dramatic changes in receptor populations of key tissues such as adipose and mammary tissues. Knowledge in this area, however, is incomplete. Relationship between hormone receptors and specific cellular metabolic pathways remains unresolved.
- Haro, L. S., Collier, R. J., & Talamantes, F. J. (1984). Homologous somatotropin radioreceptor assay utilizing recombinant bovine growth hormone. Molecular and Cellular Endocrinology, 38(2-3), 109-116.More infoPMID: 6096183;Abstract: A homologous radioreceptor assay using recombinant bovine growth hormone and bovine liver membranes is described. The total specific binding of 125I-labeled recombinant bovine growth hormone to the 100000 × g pellet was 48% in 24 h at 25 °C. Hormone binding was partially reversible, with 40% of the radiolabeled hormone being irreversibly bound. The amount of specific binding varied with assay pH, with the optimum occurring at pH 7.8. Specific binding was temperature-dependent, with greater specific binding occurring at 25°C than at 5°C or 37°C during a 24 h period. Recombinant bovine growth hormone, human growth hormone, ovine growth hormone and recombinant porcine growth hormone competed effectively with 125I-labeled recombinant bovine growth hormone for binding sites, while bovine prolactin and ovine prolactin were needed in amounts 106-fold the concentration of recombinant bovine growth hormone to displace the radiolabeled hormone. Surprisingly, human placental lactogen did not displace the radiolabeled hormone. © 1984.
- Lewis, G. S., Thatcher, W. W., Bliss, E. L., Drost, M., & Collier, R. J. (1984). Effects of heat stress during pregnancy on postpartum reproductive changes in Holstein cows.. Journal of animal science, 58(1), 174-186.More infoPMID: 6538193;Abstract: Effects of heat stress during the last third of gestation on reproductive changes postpartum were studied in Holstein cows. Cows and heifers 160 to 190 d of gestation were assigned in June 1978 to shade (n = seven cows and two heifers) or no shade (n = eight cows and two heifers) management treatments. After parturition, all cows (n = 19) were moved to the milking herd and managed uniformly. On the day of calving and on each Monday, Wednesday and Friday thereafter until d 50 postpartum, jugular blood samples were collected. Beginning approximately 7 d postpartum, the reproductive tract of each cow was examined rectally after collection of blood samples. Estrus was monitored twice daily and cows were inseminated after d 45 postpartum. Prepartum heat stress increased 13,14-dihydro-15-keto-prostaglandin F2 alpha (PGFM) concentrations postpartum and increased the rate of uterine involution. Regardless of prepartum treatment, progesterone concentrations indicated that luteal phases had begun by d 12.4 +/- 1.3 postpartum, which was about 3 d before PGFM was basal. The first luteal phase lasted only 10.7 +/- .9 d. First estrus was not detected until d 32.3 +/- 4.8 postpartum. The previously gravid uterine horn had a negative effect on ovarian volume, diameter of the largest follicle and percentage of ovaries with a corpus luteum. However, prepartum heat stress attenuated this effect. This study indicates that heat stress prepartum had residual effects on postpartum reproductive changes, and that the previously gravid uterine horn exerted some control, which was attenuated by heat stress, over ovarian recrudescense. Even though heat stress prepartum affected sensitive measures of postpartum reproductive function, it did not alter days to first estrus, days open (102.3 +/- 13.1) or services/conception (2.5 +/- .3).
- Schneider, P. L., Beede, D. K., Wilcox, C. J., & Collier, R. J. (1984). Influence of dietary sodium and potassium bicarbonate and total potassium on heat-stressed lactating dairy cows.. Journal of dairy science, 67(11), 2546-2553.More infoPMID: 6097604;Abstract: Objectives were to study effects of heat stress, 0 or .85% sodium bicarbonate, 0 or 1.0% potassium bicarbonate, and 1.0 or 1.5% total dietary potassium on production and physiological responses of dairy cows. Eighteen lactating Holsteins were assigned to shade (control) or no shade (heat stress) lots continuously for three consecutive 35-day periods and to different dietary treatments each period. Basal diet was 25% cottonseed hulls and 75% concentrate. Daytime and nighttime feed intake and production were measured the last 2 wk of each period, and milk and blood were sampled the final day of each period. Black globe temperature, rectal temperature, respiration rate, and blood pH were higher in no shade. Daytime intake was 132% greater in shade, nighttime intake was not different between environments. Milk production was about 19% greater for evening and morning milkings in shade. Daytime intake, daytime and nighttime milk production were higher with sodium bicarbonate. Potassium bicarbonate reduced intake and production. Higher total dietary potassium increased total daily milk production. Lactating cows appear adept at withstanding environmental and dietary challenges to acid-base homeostasis. Supplementation of sodium bicarbonate and 1.5% dietary potassium, but not potassium bicarbonate, were beneficial to lactating dairy cows.
- Buffington, D. E., & Collier, R. J. (1983). DESIGN PARAMETERS FOR SHADE MANAGEMENT SYSTEMS FOR DAIRY COWS IN HOT, HUMID CLIMATES.. ASAE Publication, 100-110.
- Buffington, D. E., Collier, R. J., & Canton, G. H. (1983). SHADE MANAGEMENT SYSTEMS TO REDUCE HEAT STRESS FOR DAIRY COWS IN HOT, HUMID CLIMATES.. Transactions of the American Society of Agricultural Engineers, 26(6), 1798-1802.More infoAbstract: The benefits of providing shade for dairy cows are reported based on over 8 yr of research. Production benefits that are attributable to a well-designed shade management system are increases in milk production, reproductive efficiency and milk production in subsequent lactation. Major design and management considerations for shade management structures that are presented and discussed are orientation, space, floor, height, ventilation, roof construction, feeding and watering facilities, and waste management system.
- Kensinger, M. H., Collier, R. J., Wilcox, C. J., & Caton, D. (1983). Variability of resting mammary blood flow in nonlactating Holstein cows.. Journal of dairy science, 66(8), 1742-1746.More infoPMID: 6619351;
- Sharma, A. K., Rodriguez, L. A., Mekonnen, G., Wilcox, C. J., Bachman, K. C., & Collier, R. J. (1983). Climatological and genetic effects on milk composition and yield.. Journal of dairy science, 66(1), 119-126.More infoPMID: 6833586;Abstract: Results confirm most other research on milk composition and yield. All responses were affected by climate, some considerably more than others, if percent of error variance is the criterion. Jersey yields were less sensitive to climate than were Holstein, but Jersey milk composition appeared more sensitive. Somatic cell count (REF), a measure of mastitis, was affected by climate but less than all other variables except protein/fat and LM%. Needed are estimates of interactions between climatic effects and response surface models to quantify possible improvement in performance following environmental modification. Genetic correlations between milk yield and REF and chloride % suggest that single trait selection for milk yield might increase incidence of mastitis although phenotypic correlations indicate that high yields and absence of mastitis are correlated.
- Beede, D. K., Collier, R. J., Mallonee, P. G., Wilcox, C. J., & Buffington, D. E. (1982). HEAT STRESS AND DIETARY POTASSIUM EFFECTS ON CIRCADIAN PROFILES OF BLOOD PROLACTIN AND ALDOSTERONE IN LACTATING COWS.. ASAE Publication, 556-556.
- Buffington, D. E., Collier, R. J., & Canton, G. H. (1982). SHADE MANAGEMENT SYSTEMS TO REDUCE HEAT STRESS FOR DAIRY COWS.. Paper - American Society of Agricultural Engineers.
- Collier, R. J., Beede, D. K., Thatcher, W. W., Israel, L. A., & Wilcox, C. J. (1982). Influences of environment and its modification on dairy animal health and production.. Journal of dairy science, 65(11), 2213-2227.More infoPMID: 6759540;Abstract: Physiological state of dairy animals is a predisposing factor in environmental influences on animal health. Critical phases of life cycle include neonatal period, postpubertal reproduction, and lactation. Primary effect of environment in neonatal period is increased disease incidence associated with reduced immunoglobulin content in plasma of calves. Cold stress has little effect on reproduction; in contrast, heat stress reduces libido, fertility, and embryonic survival in cattle. Heat stress in late gestation reduces fetal growth and alters endocrine status of the dam. Carryover effects of heat stress during late gestation on postpartum lactation and reproduction also are detectable. Heat stress of lactating cattle results in dramatic reductions in roughage intake and rumination. Decreases in roughage intake contribute to decreased volatile fatty acid production and may contribute to alteration in ratio of acetate/propionate. Rumen pH also declines during thermal stress. Electrolyte concentrations, in particular sodium and potassium, also are reduced in rumen fluid of heat stressed cattle. The decrease in sodium and potassium are related to increases in loss of urinary sodium and loss of skin potassium as well as decline in plasma aldosterone and increase in plasma prolactin. Reduction in thyroxine, growth hormone, and glucocorticoid concentrations in chronically heat stressed cattle appear to be related to decreases in basal metabolism.
- Collier, R. J., Doelger, S. G., Head, H. H., Thatcher, W. W., & Wilcox, C. J. (1982). Effects of heat stress during pregnancy on maternal hormone concentrations, calf birth weight and postpartum milk yield of Holstein cows.. Journal of animal science, 54(2), 309-319.More infoPMID: 7076593;Abstract: For an evaluation of the effects of heat stress during pregnancy on calf birth weight and postpartum maternal milk yield, 21 cows and 10 heifers were assigned to shade (S; n = 16) or no shade (NS; n = 15) treatments during the last trimester of pregnancy in June 1978. At parturition, all cows were removed from treatment and uniformly managed in the milking herd. At 4-d intervals from d 199 of pregnancy to parturition, respiration rates, rectal temperature, heart rate and Black Globe temperature were recorded and blood samples obtained via tail venipuncture between 1300 and 1600 h. Weekly prepartum body weights of dam, birth weight of calf and subsequent daily milk yield were recorded. Black Globe temperature, rectal temperature and respiration rates were higher in cows given NS. Calf birth weight was lower in the NS group. Milk yield was correlated in a linear manner with calf birth weight, and cows in group NS exhibited reduced lactation performance after calving. Plasma progestin concentrations were higher in heat-stressed cows (6.0 vs 5.1 ng/ml). Estrone-sulfate concentrations were reduced in plasma of NS cows (2,505 vs 4,433 pg/ml). Thus, hormone concentrations of maternal and fetal origin were altered by environment. Plasma thyroxine concentrations were lower in NS cows (51.2 vs 66.4 ng/ml), while plasma triiodothyronine concentrations were elevated (1.8 vs 1.5 ng/ml), indicating altered thyroid hormone metabolism in heat-stressed cows. Heat stress altered endocrine dynamics during pregnancy and reduced calf birth weight and may have indirectly altered subsequent milk yield.
- Kensinger, R. S., Collier, R. J., Bazer, F. W., Ducsay, C. A., & Becker, H. N. (1982). Nucleic acid, metabolic and histological changes in gilt mammary tissue during pregnancy and lactogenesis.. Journal of animal science, 54(6), 1297-1308.More infoPMID: 6179921;Abstract: Changes in mammary gland histology, dry weights, nucleic acids and in vitro rates of substrate oxidation in incorporation into lipid were measured in mammary biopsies of three gilts each on d 30, 45, 60, 75, 90, 105 and 112 of pregnancy, and d 1 and 4 of lactation. Histological changes noted were progressive duct growth early in pregnancy followed by rapid lobulo-alveolar development between d 75 and 90 to complete mammogenesis. Colostrum and lipid were evident by d 105 with marked distension of alveolar lumina on d 112. Complete differentiation of the secretory process was apparent on the day of parturition. Concentrtion of dry, fat-free tissue (DFFT) and DNA changed little before d 60 but increased fourfold between d 75 and 90. No further increases in DFFT or DNA were noted. RNA concentrations paralleled DNA through d 90, after which they steadily increased. Rates of acetate and glucose oxidation increased transiently during midpregnancy then declined and remained low until initiation of lactogenesis. Substrate incorporation into lipid increased slightly at midpregnancy and again at d 105, after which it increased markedly. Collectively, results indicate that mammogenesis is complete by d 90, after which lactogenesis is initiated in a two-stage process. Metabolic rates expressed on a DNA basis indicated considerable rates of oxidation, but not of lipogenesis by proliferating mammary tissue. Preferential metabolism of acetate vs glucose near parturition suggests coordination of metabolism between the mammary gland and other maternal tissues.
- Eley, D. S., Thatcher, W. W., Head, H. H., Collier, R. J., & Wilcox, C. J. (1981). Periparturient endocrine changes of conceptus and maternal units in Jersey cows bred for milk yield.. Journal of dairy science, 64(2), 296-311.More infoPMID: 7276313;Abstract: Control cows, sired by and bred to bulls with assumed zero estimated breeding values, and selected cows, sired by and bred to bulls of high predicted difference for milk yield, were used. Blood samples were collected via jugular venipuncture on alternate days from 35 to 14 days prepartum, from 14 to 28 days postpartum, and daily from 14 days prepartum to 14 days postpartum. We examined blood hematocrit, and concentrations in plasma of protein, estrone, estradiol, estrone sulfate, progestins, glucocorticoids, luteinizing hormone, and prolactin. Total plasma volume was measured on days -21, -7, and +11. Weekly body weights, prepartum and postpartum, were recorded. All data were analyzed by least squares analysis of variance with day and hematocrit as continuous independent variables. Hematocrit was higher for selected cows throughout the sampling period. Prepartum concentrations of progesterone were higher in selected cows, but concentrations of estrone, luteinizing hormone, and prolactin were lower than in control cows. Hormonal and physiological responses indicated that selection for milk yield influenced both the conceptus and maternal units as measured by prepartum endocrine function.
- Eley, D. S., Thatcher, W. W., Head, H. H., Collier, R. J., Wilcox, C. J., & Call, E. P. (1981). Periparturient and postpartum endocrine changes of conceptus and maternal units in Jersey cows bred for milk yield.. Journal of dairy science, 64(2), 312-320.More infoPMID: 7276314;Abstract: Control cows, sired and bred by bulls of zero estimated breeding value, and selected cows, sired by and bred to bulls of high predicted differences for milk yield, were used to evaluate maternal endocrine changes from 14 days prepartum to 28 days postpartum. Examined were concentrations in plasma of 13, 14 dihydro-15 keto-prostaglandinF2 alpha, progesterone, estrone sulfate, estrone, luteinizing hormone, and prolactin. Ability of cows to release prolactin and luteinizing hormone on day 10 postpartum was evaluated after a simultaneous injection of thyrotropin releasing hormone (100 microgram) and gonadotropin releasing hormone (100 microgram). Changes in progesterone and estrogens prepartum lead to peak concentrations of prolactin and prostaglandin at parturition and 3 days postpartum, respectively. Higher basal concentrations of prolactin for control cows prepartum were associated with a higher prolactin release by thyrotropin releasing hormone at 10 days postpartum. Although release of luteinizing hormone in response to gonadotropin releasing hormone did not differ between groups on day 10 postpartum, a subsequent increase in progesterone to above 1 ng/ml was earlier and more precisely synchronized among control cows (16 +/- .43 versus 23 +/- 2.33 days). Within cow concentrations of F2 alpha 13, 14 dihydro-15-keto-prostaglandin-F2 alpha were correlated with size of previous gravid uterine horn (.67) and milk yield (-.39). Selection for milk yield influenced postpartum endocrine function.
- Roman-Ponce, H., Thatcher, W. W., Collier, R. J., & Wilcox, C. J. (1981). Hormonal responses of lactating dairy cattle to TRH and ACTH in a shade management system within a subtropical environment. Theriogenology, 16(2), 131-138.More infoAbstract: Lactating cows (64) were balanced by breed (54 Holstein and 10 Jersey) and assigned randomly to shade (S) or no shade (NS) management treatments for a continuous 20 wk trial beginning 5-5-76. A sub-sample of Holstein cows, five S and five NS, were fitted with jugular catheters 84 days after initiation of experiment. Thyrotropin Releasing Hormone (TRH; 100 μg) was administered intravenously at 1200 h to evaluate prolactin responses. Two days later each cow received intravenously 200 IU of ACTH at 1100 h to compare acute corticoid responses to ACTH. Mean prolactin response to TRH was greater for NS cows (291 vs 169 ng/ml; P < .01) as was peak plasma concentrations at 20 min (467 vs 267 ng/ml; P < .01). Mean corticoid response to ACTH injection was less for NS cows (52 vs 70 ng/ml; P < .10). Corticoid concentrations of plasma in both treatments had declined 65% by 7 h postinjection. These endocrine differences may be associated with thermoregulation and/or metabolic adjustments of cows exposed to different environmental systems of management during a seasonal period of thermal stress. © 1981.
- Canton, G. H., Buffington, D. E., & Collier, R. J. (1979). INSPIRED-AIR COOLING FOR DAIRY COWS.. Paper - American Society of Agricultural Engineers.More infoAbstract: Benefits of inspired-air cooling for dairy cows were evaluated for inspired air temperatures of 10, 15, and 21 degree C. Inspired air temperatures of 10 and 15 degree C effectively reduced both respiration rates and rectal temperatures compared to the controls. The maximum inspired air temperature to effectively reduce heat stress in dairy cows is 18-19 degree C. Maximum benefits for reducing heat stress can be achieved by providing both inspired-air cooling and shading. Refs.
- Collier, R. J., Haynes, N. B., Kiser, T. E., & Hafs, H. D. (1979). Serum glucocorticoids, growth hormone and insulin and plasma glucose in bulls given prostaglandin E2 or F2 alpha 1.. Journal of animal science, 49(6), 1517-1521.More infoPMID: 393692;Abstract: Plasma glucose and serum insulin, growth hormone and glucocorticoid concentrations were determined in five yearling bulls given (im) 5, 15 or 30 mg prostaglandin E2 (PGE2), 30 mg prostaglandin F2 alpha(PGF2 alpha) or saline. Jugular blood was collected at frequent intervals around the time of injection and at .5--hr intervals from 1 to 9 hr after injections. Thirty milligrams PGE2 and 30 mg PGF2 alpha each caused 15- to 20-fold increases in serum glucocorticoids. Glucocorticoids increased with increasing doses of PGE2. Although PGE2 and PGF2 alpha each increased blood growth hormone, this effect was about twofold larger after PGE2. By contrast, PGE2 depressed serum insulin about 50% for 1 hr, then insulin increased about sixfold until 3 to 4 hours. Blood serum insulin increased after PGF2 alpha, but this effect only approached significance (P less than .10). Plasma glucose increased about 10 mg/100 ml after PGE2, but was not affected significantly by PGF2 alpha. Thus, the effects of PGE2 and PGF2 alpha on hormones which control glucose metabolism differ markedly. We speculate that PGE2 caused a twofold increase in growth hormone secretion within 10 to 20 min, that increased growth hormone induced increased blood glucose within 1 to 2 hr and that increased glucose caused increased insulin secretion at 2 to 4 hr, but we cannot rule out a transitory (1 hr) suppressive effect of PGE2 directly on the pancreas.
- Kensinger, R. S., Bauman, D. E., & Collier, R. J. (1979). Season and treatment effects on serum prolactin and milk yield during induced lactation.. Journal of dairy science, 62(12), 1880-1888.More infoPMID: 541460;Abstract: Nineteen nonpregnant, nonlactating dairy cows were allotted to three treatments to induce lactation during winter, 1976, or spring, 1977. All groups received 17 beta-estradiol (.1 mg/kg) days 1 to 7. Groups 2 and 3 also received progesterone (.25 mg/kg) days 1 to 7. Groups 1 and 2 were given reserpine (5 mg intramuscular) on days 8, 10, 12, and 14. Group 3 received reserpine (5 mg intramuscular) on days 2, 5, 8, 11, and 14. Blood samples were collected for prolactin analysis just prior to and 3 h after reserpine injection. Mean daily temperatures were 11.9 C for spring group and -6.5 C for winter group. Comparisons of spring with winter for basal prolactin concentrations, reserpine-stimulated prolactin concentrations, and 100-day milk yields were 44 with 10 ng/ml, 482 with 199 ng/ml, and 1991 with 862 kg. Differences in prolactin concentrations and milk yields among hormone and reserpine treatments could not be detected, but cows on treatment 3 in the spring gave the largest yield of milk. Prolactin concentrations were correlated with milk yields among cows and among cows within seasons. Seasonal differences demonstrate the critical role of prolactin in the treatment to induce lactation.
- Collier, R. J., & Tucker, H. A. (1978). Regulation of cortisol uptake in mammary tissue of cows.. Journal of dairy science, 61(12), 1709-1714.More infoPMID: 744807;Abstract: Mammary tissue explants from four nonlactating, nonpregnant cows were placed into culture with media containing various combinations of insulin, prolactin, growth hormone, 17beta-estradiol, dexamethasone, and progesterone. Combinations of insulin, prolactin, growth hormone, or 17beta-estradiol had no effect on cytoplasmic or nuclear uptake of tritiated cortisol compared with values at zero time. Combinations containing dexamethasone of progesterone reduced cytoplasmic and nuclear uptake of tritiated cortisol. To examine inhibition by progesterone of binding of tritiated cortisol, mammary tissue from each of four lactating, nonpregnant and four nonlactating, nonpregnant cows were placed in flasks containing tissue culture medium 199, tritiated cortisol (2 ng/ml), and progesterone at concentrations of 0, 10(-12), 10(-11), 10(-10), 10(-9), 10(-8), 10(-7), 10(-6), or 10(-5) X 6.4 M. Cytoplasmic uptake of tritiated cortisol into nonlactating tissue decreased linearly as progesterone increased, whereas tritiated cortisol uptake in lactating tissue did not decrease until progesterone exceeded 10(-7) M. We postulated progesterone is sequestered in milk fat of cytoplasm of lactating tissue whereas in nonlactating tissue progesterone is available to compete with cortisol at sites of cortisol binding.
- Haynes, N. B., Collier, R. J., Kiser, T. E., & Hafs, H. D. (1978). Effect of prostaglandin E2 and F2alpha on serum luteinizing hormone, testosterone and prolactin in bulls.. Journal of animal science, 47(4), 923-926.More infoPMID: 738978;
- Bauman, D. E., Collier, R. J., & Tucker, H. A. (1977). Effect of reserpine on serum prolactin, growth hormone and glucocorticoids in dairy cows. Proceedings of the Society for Experimental Biology and Medicine, 155(2), 189-192.More infoPMID: 866347;Abstract: Nonlactating, nonpregnant Holstein cows were used to examine the effects of an im injection of reserpine. A 5-mg reserpine injection resulted in a rapid (within 0.5 hr) and sustained (at least 24 hr) elevation of serum prolactin. Peak prolactin levels (283 ng/ml) occurred 3 hr postinjection. Serum glucocorticoid and growth hormone concentrations were unaffected by reserpine injection. Two sequential injections of 5 mg of reserpine given at 48-hr intervals gave nearly identical prolactin responses. The prolactin response to reserpine was dose dependent with 1 mg giving approximately 39.5% of the response obtained with 5 mg of reserpine.
- Collier, R. J., Bauman, D. E., & Hays, R. L. (1977). Effect of reserpine on milk production and serum prolactin of cows hormonally induced into lactation.. Journal of dairy science, 60(6), 896-901.More infoPMID: 559698;
- Collier, R. J., Bauman, D. E., & Hays, R. L. (1977). Lactogenesis in explant cultures of mammary tissue from pregnant cows. Endocrinology, 100(4), 1192-1200.More infoPMID: 837880;Abstract: The hormonal requirements for lactogenesis were investigated using explant cultures of mammary tissue obtained from cows at 30-40 days prepartum. Hormones used were insulin, hydrocortisone, and prolactin, and parameters examined were radioactive acetate incorporation into fatty acids, secretory response ratings, and histological and ultrastructural analysis. Data indicated that insulin was essential for mammary epithelial cell survival, but insulin alone did not result in the initiation of milk synthesis. The culture of explants in a medium containing insulin plus hydrocortisone resulted in alterations in the cytology of alveolar cells but no induction of milk synthesis. Biosynthesis results and secretory response ratings indicated that the initiation of milk synthesis occurred when explants were cultured in insulin and prolactin; however, synthesis was limited and alveolar integrity was not well maintained. Results from all parameters demonstrated that the maximal lactogenic response was obtained when the culture medium contained insulin, hydrocortisone and prolactin. After 48 h of culture in this medium, the rate of acetate incorporation into fatty acids had increased 3-fold and the markedly distended alveolar lumina contained many fat droplets and abundant eosinophilic staining secretion. However, an unusual amount of casein-like micelles and especially lipid also accumulated in the alveolar cells. The accumulation of milk components within the epithelial cells may be related indirectly to the accumulation of products in the lumina or perhaps related to a difference in the hormonal requirement between the initiation of milk synthesis and initiation of milk secretion.
- Ax, R. L., Collier, R. J., & Lodge, J. R. (1976). Effects of dietary caffeine on the testis of the domestic fowl, Gallus domesticus. Journal of Reproduction and Fertility, 47(2), 235-238.More infoPMID: 957321;Abstract: Roosters were fed 0.1% caffeine mixed by weight into a standard ration. With continued dietary caffeine administration, the average fertility of eggs collected for 2 weeks from untreated pullets inseminated with semen from the treated males at 0, 7 and 14 days after the start of treatment was 30.8, 33.5 and 3.3%, respectively. After 14 days of treatment fertility was significantly lower (P
- Collier, R. J., Croom, W. J., Bauman, D. E., Hays, R. L., & Nelson, D. R. (1976). Cellular studies of mammary tissue from cows hormonally induced into lactation: lactose and fatty acid synthesis.. Journal of dairy science, 59(7), 1226-1231.More infoPMID: 985832;Abstract: Temporal changes in ability of mammary gland to synthesize lactose and fatty acids were identified during the treatment of cows hormonally induced to lactate, and animal differences were compared to subsequent milk production. Hormonal treatment involved 17 beta-estradiol + progesterone on days 1 to 7 and dexamethasone on days 17 to 19. Mammary tissue obtained by biopsy on days 0, 8, 16, and 26 of treatment was examined for biosynthetic capacity by tissue slice incubations. In terms of peak daily milk yield, one cow was very successful (greater than 30 kg), two were intermediate (9 to 10 kg), and one cow was unsuccessful (less than 3 kg). Differences between cows in the capability to synthesize lactose and fatty acids were evident as early as day 8 and were further magnified by day 16. In particular, the tissue from the successful cow was undergoing lactogenesis by day 8 while this was not evident until the day 16 biopsy sample in the less successful cows. In contrast to the other cows, tissues from the unsuccessful animal regressed in its ability to synthesize lactose and fatty acids between day 16 and 26. Relative differences between animals in measurements of metabolic capacity were consistent with subsequent milk production.
- Croom, W. J., Collier, R. J., Bauman, D. E., & Hays, R. L. (1976). Cellular studies of mammary tissue from cows hormonally induced into lactation: histology and ultrastructure.. Journal of dairy science, 59(7), 1232-1246.More infoPMID: 985833;Abstract: Cytological changes were investigated in mammary parenchyma of cows hormonally induced to lactate. Four cows were induced with injections of 17 beta-estradiol plus progesterone (days 1 to 7) and dexamethasone (days 17 to 19). Tissue biopsies were obtained on days 0, 8, 16, and 26; and milking commenced on day 18 or 21 of the treatment period. Mammary tissue of cow A, the most successful animal, showed marked cellular proliferation and differentiation by day 8. By day 16, the parenchyma of cow A had undergone lactogenesis and exhibited histological and ultrastructural characteristics associated with actively secreting mammary tissue. Mammary epithelia of cow D, the least successful animal, showed minimal development by day 8 and ultrastructurally resembled nondifferentiated mammary cells. Mammary parenchyma of cow D had not undergone differentiation and was involuting by day 16. Mammary tissues of cow B and C showed intermediate responses with only slight development by day 16 and only limited areas of secretory activity by day 26. Results suggest that animals successfully induced into lactation undergo critical periods of cellular proliferation and differentiation which unsuccessful animals do not experience. Cytological differences were first evident by day 8, further magnified by day 16 of the treatment period, and subsequently expressed in terms of milk production (peak milk yield equaled 30.5, 10.0, 9.2, and 2.4 kg/day for cows A, B, C, and D).
- Collier, R. J. (2015, Feb/Spring). Advances in Dairy Production and Nutrition. In 4th International Symposium on Dairy Cow Nutrition and Milk Quality/Beijing, China, -, 1-8.
- Collier, R. J. (2015, sept). .Recombinant bovine somatotropin: Overview and results from a recent meta-analysis of effects on health and welfare of dairy cows.. In American Association of Bovine Practitioners.More infoHistorically, the dairy industry has made remarkable gains in productivity and a gallon of milk can be produced today with less feed resource inputs and a markedly reduced carbon footprint. Recombinant bovine somatotropin is a production-enhancing technology and 20 years commercial use of POSILAC® (rbST-Zn) provided the backdrop for an updated meta-analysis of effects on cow health and welfare. Our meta-analysis used data from peer reviewed publications or regulatory reports in which the commercial formulation of rbST-Zn was used was according to label specifications.29 Twenty six studies were identified which had usable data (13,784 cows). Results indicated milk yield was increased by about 9 lb/d whereas milk fat, protein, and lactose content were unaltered. For health and welfare variables, treatment with rbST-Zn had little or no effect on udder health, reproduction, lameness, body condition or culling. Overall, these results and 20 years of US commercial experience demonstrate that management practices used by US dairy producers are adequate for the effective use of rbST-Zn to increase milk yield and productivity with no unmanageable adverse effects on cow health or welfare.
- Collier, R. J. (2014, February). Impacts of Heat Stress on Immune Function of Cattle. In Florida Nutrition Conference, 25, 16-27.More infoHeat stress exposure was mild to moderate in this study. The threshold for heat stress in lactating dairy cows is a THI > 68, respiration rates > 60 bpm and rectal temperatures > 38.5°C (Zimbleman et al., 2009). OmniGen-AF reduced impact of thermal stress on stress on lactating dairy cows. Cows fed Omnigen-AF had reduced rectal temperatures and respiration rates during periods of peak thermal load. Respiration rates in treated cows did not exceed 60bpm and mean rectal temperatures were 0.2 – 0.3°C cooler. OmniGen-AF fed cows displayed higher feed intakes during heat stress as well. Cows fed Omni-Gen AF also displayed a lower cortisol spike on the first day of heat stress. Milk yield decreased with heat stress in both control animals and the OmniGen-AF fed animals. However, feed intake was unchanged in cows fed Omnigen-AF and milk yields were numerically higher. Changes in SCC were consistent between groups. Cows fed OmniGen-AF displayed decreased SCC compared to control with the greatest difference during the recovery period. Serum cortisol levels were similar to previous finding (Christison and Johnson, 1972) and increased within the first day of heat exposure. The animals in the ARC had higher cortisol levels compared to published levels, but the confinement and changes in surrounding from the dairy to the ARC may account for some of the changes. Cytokine (RANTES) gene expression was higher in cows fed Omnigen-AF during the heat stress portion of the study but not during recovery. The elevated cytokine gene expression may be associated with improved immune function in cows fed Omnigen- AF
- Collier, R. J. (2014, February). update on Human Health Concerns of Recombinant Bovine Somatotropin (rbST) Use in Dairy Production. In Southwest Nutrition and Management Conference, 29, 78-87.More info• After 20 years of continuous use in the US, there are no new animal or human health issues related to the use of rbST by the dairy industry• No evidence that rbST use has increased human exposure to milk containing antibiotic residues • Oral consumption of IGF-I by humans has little or no biological activity and chronic supplementation of cows with rbST does not increase milk IGF-I concentration outside the range typically observed for effects of farm, parity, or stage of lactation• No evidence of increased risk for development of Type I or Type II diabetes in children or adults consuming milk and dairy products from rbST-supplemented cows• Milk and dairy products provide essential nutrients and related benefits in health maintenance and the prevention of chronic diseases; milk composition is unaltered by use of rbST
- Collier, R. J. (2014, October). AN UPDATE ON rBST - HUMAN HEALTH, ANIMAL HEALTH, AND WELFARE CONSIDERATIONS. In Cornell Nutrition Conference, 76, 26-36.More infoResults of the meta-analysis carried out by St-Pierre et al, 2014 indicated that administration of the commercially available rbST formulation to lactating dairy cows according to FDA-approved label directions resulted in an increase in milk, fat, and protein yields with no unmanageable adverse effects on milk composition (percentages of fat, protein, and lactose in milk), udder health, reproduction, body condition, lameness, or culling. These findings were in line with conclusions of various FDA evaluations, USFDA, 2014, scientific reviews, Crooker et al. 1991, Bauman,1992 and large-scale studies conducted on commercial dairy operations, Ruegg et al.,1998, Collier et al. 2001.
- Bauman, D., & Collier, R. (2012, Fall). Developing the research question, hypothesis, design, and protocol. In Not provided in APROL, 90, 692.
- Collier, R., Hall, L., & Rungruang, S. (2012, Fall). ESTIMATING IMPACTS OF HEAT STRESS ON NIACIN METABOLISM AND PERFORMANCE OF LACTATING DAIRY COWS. In Proc. 74th Cornell. Nutr. Conf., 18-25.
- Godfrey, R., Weis, A., Hillman, P., Gebremedhin, K., Lee, C., & Collier, R. (2012, Fall). Evaluation of body temperature and sweating rate of Senepol and crossbred heifers in the tropics. In Not provided in APROL, 90, 240.
- Godfrey, R., Weis, A., Hillman, P., Gebremedhin, K., Lee, C., & Collier, R. (2012, Fall). Evaluation of body temperature and sweating rate of Senepol cows in the tropics. In Not provided in APROL, 90, 241.
- Rungruang, S., Collier, J., & Collier, R. (2012, Fall). Effect of niacin on heat shock protein gene expression in transformed bovine mammary epithelial cells. In Not provided in APROL, 90, 556.
- Stemm, K., Jones, C., Collier, J., & Collier, R. (2012, Fall). Evaluation of mitogenic properties of colostrum and colostrum replacer (CR) on growth of bovine mammary epithelial cells (BMEC) in vitro. In Not provided in APROL, 95, 553.More infoJ. Dairy Sci.
- Xiao, Y., Collier, J., Rungruang, S., Hall, L., Dunshea, F., & Collier, R. (2012, Fall). Effects of betaine on heat induced heat shock protein expression in primary bovine mammary epithelial cells. In Not provided in APROL, 90, 566.
- Collier, R. J. (2015, October). Thermal Biology of domestic animals. CEVA’s ReprodAction ScientificMeeting Series: Panel of Experts Effect of Heat Stress on Cattle Reproduction. Verona, Italy: Ceva Sante Animale.
- Collier, R. J. (2015, july). Heat Stress Abatement Strategies. Addisseo Conference on Dairy Nutrition in China. Beijing, China: Adisseo Company.
- Collier, R. J. (2015, sept). Estrategias de manejo en al Estrès Calórico en la zona de Querètaro (Strategies to reduce heat stress in lactating dairy cows ). Memorias 5th Annual Simposio. Queretero, Mexico: Ganaderos Asociados de Querétaro (GAQSA).
- Ortiz, X. A., Smith, J. F., Vilar, F., Hall, L. W., Allen, J. D., Odde, A., Al-Haddad, A., & Collier, R. J. (2015, july). A. comparison of two evaporative cooling systems on a commercial dairy farm in Saudi Arabia.. Joint ASAS/ADSA Meeting. Orlando, florida: American Society of Animal Science and American Dairy Science Association.More infoEfficacy of two cooling systems, (Korral Kool®, KK; Korral Kool Inc., Mesa, AZ, FlipFan® dairy system, FF; Schaefer Ventilation Equipment LLC, Sauk Rapids, Mn) was estimated utilizing four hundred multiparous Holstein dairy cows randomly assigned to one of 4 cooled California style shade pens (2 shade pens per cooling system). Each shaded pen contained 100 cows (DIM = 58 ± 39 days, milk production = 56 ± 18 kg/day and lactation = 3 ± 1). Production data (milk yield and reproductive performance) were collected during three months (June-August, 2013) and physiological responses (core body temperature, respiration rates, surface temperatures and resting time) were measured, in June and Julyto estimate responses of cows to the two different cooling systems. Water and electricity consumption were recorded for each system. Cows in the KK system displayed slightly lower respiration rates in the month of June and lower surface temperatures in June and July. However, no differences were observed in the core body temperature of cows, resting time, feed intake, milk yield, services/cow and conception rate between systems. The FF system utilized less water and electricity during this study. In conclusion both cooling systems (KK and FF) are effective in mitigating the negative effects of heat stress on cowshoused in arid environments while the FF system consumed less water and electricity and did not require use of curtains on the shade structure.
- Collier, R. J. (2014, July). The effects of OmniGen-AF on serum metabolites and calcium concentrations and hormones of the adrenal axis during heat stress in lactating Holstein cows. Joint Meeting of American Dairy Science and American Society of Animal Science Meetings. Kansas City, Kansas: American Dairy Science Association and American Society of Animal Science.More infoHolstein cows (n=30) were balanced by DIM, milk production and parity (91 ± 5.9 DIM, 36.2 ± 2.5 kg/d, and 3.1 ± 1.4) and fed OmniGen-AF (OG) for 52 days on a commercial dairy. . At 52 d of lactation cows were randomly selected (n = 12) from both groups (6 OG and 6 CON) and housed in environmentally controlled modules for 21 d at the University of Arizona. The OG was top-dressed 2x/d with molasses as the carrier and the CON cows received the molasses carrier 2x/d. Both were mixed into the top one-third of the TMRA subset (n= 12) were then transported to the University of Arizona The . Cows were subjected to 7 days of TN conditions, 10 days of HS, and 4 days of recovery (TN). Feed intake, milk production, and milk composition were measured daily. Rectal temperatures and respiration rates were recorded 3x /d (600, 1400, and 1800 h). Blood samples were taken on days 7 (TN), 8 (HS), 10 (HS), 17 (HS) and 18 (TN) during the ARC segment. Serum Cortisol levels were highest on day 8 and OG treated cows had significantly lower serum cortisol and on day 8 (con 0.8372 ug/dL, OG 0.4838 ug/dL, P
- Collier, R. J. (2014, July,). Conductive cooling as an alternative to cool down. Joint Meeting of American Dairy Science and American Society of Animal Science Meetings. Kansas City, Kansas: American Dairy Science Association and American Society of Animal Science.More infoThe typical cooling system utilized to reduce heat stress indairy operations requires high energy and/or water usage.With the steady increase in electricity costs and reduction ofwater availability and increase in water usage regulations,passive cooling systems need to be investigated as ways tocool cows and reduce the utilization of water and electricity.An experiment was designed to investigate the use of heat exchangersburied 25 cm below the surface as components in aconductive system for cooling cows. Six cows were housedin environmentally controlled rooms with tie-stall beds thatwere equipped with a heat exchanger and filled with 25 cm ofeither sand or dried manure. Beds were connected to supplyand return lines and individually controlled. Two beds (oneper each kind of bedding material) constituted a control group(water OFF), and the other four (two sand and two dried manure)used water at 7°C passing through the heat exchangers(water ON). The experiment was divided in two periodsof 40 d, and each period involved three repetitions of threedifferent climates (hot dry, thermo neutral, and hot humid).Sand bedding remained cooler than dried manure beddingin all environments and at all levels of cooling (water ONor OFF). Bed temperatures were lower and heat flux higherduring the Sand ON bed treatment. We also detected a reductionin the core body temperatures (CBT), the respirationrates (RR), rectal temperatures, and skin temperatures of thosecows heat-stressed during the Sand ON treatment. Dry matterintake and milk yield numerically increased during the SandON bed treatment for all climates. No major changes wereobserved in the lying time of cows or the composition of themilk produced. We concluded that use of heat exchangers isa viable alternative to systems that employ fans, misters, andthe evaporative cooling methods to mitigate the effects of heatstress in dairy cows. Sand was a better bedding material touse in combination with heat exchangers. Additional researchis needed to investigate alternative ways to increase the exchange of heat through conduction. Future studies should investigatethe benefits of placing the heat exchanger closer tothe skin surface and further reducing the water temperaturethrough mechanical cooling.
- Collier, R. J. (2014, July,). Serotonin (5-HT) receptor expression in bovine apocrine sweat gland epithelial cells isolated from cow skin. Joint Meeting of American Dairy Science and American Society of Animal Science Meetings. Kansas City, Kansas: American Dairy Science Association and American Society of Animal Science.More infoApocrine sweat glands in bovine skin are involved in thermoregulation.Human, horse, and sheep sweat gland epithelialcells have been isolated and grown in vitro. However,isolation of bovine sweat gland epithelial cells (BSGEC) hasnever been reported. Recent studies have demonstrated thatserotonin (5-HT) is an important local regulator of lactationalhomeostasis and involution in bovine, mouse, and humanmammary epithelial cells. We hypothesized that, since themammary gland is a modified sweat gland, that 5-HT receptorsmay also be present in BSGEC. The present study wasconducted to identify a method to isolate bovine sweat glandsand culture apocrine BSGEC in vitro and evaluate the expressionof 5-HT receptors (1B, 2A, 2B, 4, and 7) in bovineskin, intact apocrine sweat glands and BSGEC. Collagenasedigestion, neutral red staining and mechanical shearing wereused to identify and isolate the apocrine glands from skin.The isolated material was transferred to complete media (keratinocyteserum-free media, K-SFM), bovine pituitary extract(BPE), and human recombinant epidermal growth factor(EGF) + 2.5% FBS in a T25 flask with media film then incubatedat 37°C for 24 h. After sweat glands adhered to thebottom, an additional 2 mL of complete media was added,and the media was changed every 3 d. Isolated apocrine sweatglands and BSGEC were immunostained for cytokeratin andfibroblast specific protein, indicating fibroblast-free cultures.We also determined the mRNA expression of bovine 5-HTreceptor subtypes in bovine whole skin, sweat glands, andBSGEC. The mRNAs for 5 receptor isoforms (5-HT 1B, 2A,2B, 4, and 7) were identified by conventional PCR. We identifiedisoforms 5HT 1B, 2A, 2B, 4, and 7 in whole skin; 1B,2B, and 7 in isolated sweat glands and BSGEC. We report amethod for the isolation of bovine apocrine sweat glands andsuggest that keratinocyte medium supplemented with 2.5%FBS is effective and suitable for the culture of BSGEC. Thepresence of 5-HT receptors in BSGEC indicates that the serotonergicsystem is involved in regulation of BSGEC function.
- Collier, R. J. (2014, july). Update on animal health concerns of recombinant bovine somatotropin (rbST): Metaanalysis. Joint Meeting of American Dairy Science and American Society of Animal Science Meetings. Kansas City, Kansas: American Dairy Science Association and American Society of Animal Science.More infoThe commercial form of recombinant bovine somatotropin,sometribove zinc formulation (rbST-Zn), was approved byFDA as safe and has been successfully used by the U.S. dairyindustry since 1994. However, a meta-analysis by an expertpanel assembled at the request of Health Canada concludedthat the commercial use of rbST would cause serious healthand welfare problems. The present investigation utilized a seriesof meta-analyses to re-evaluate the efficiency and safetyof rbST-Zn when used according to label. A total of 26 studiesmet the criteria: 1) published in peer-reviewed journals or reviewedby regulatory agencies, 2) used the rbST-Zn formulation(Posilac) available to U.S. producers, and 3) used accordingto label for dose (biweekly), treatment initiation (57–70 dpostpartum), and administration method (subcutaneous injection).Meta-analysis results indicated that milk, fat, protein, and3.5% fat-corrected milk yields were all increased (P < 0.001)by rbST-Zn (average of 4.00, 0.144, 0.137, and 4.04 kg/d, respectively),whereas milk concentrations of fat, protein, andlactose were unaltered (P < 0.09, 0.07, and 0.26, respectively).A 5.4% improvement in pregnancy proportion from rbST-Znwas detected for the first two breeding cycles after the voluntarywait period (P < 0.01). However, a 5.5% decrease (P
- Collier, R. J. (2012). Metabolic Health of the Bovine Mother. 62nd Annual Meeting European Animal Production Conference. Stavanger, Norway.
- Collier, R. J. (2012). New Concepts on Impact of Thermal Stress on Lactation in Dairy Cows. Madison, Wisconsin: University of Wisconsin, Dairy Science Department Seminar.
- Collier, R. J. (2012). Serotonin as a Homeostatic Regulator of Bovine Lactation. 7th International Congress on Farm Animal Endocrinology. Berne, Switzerland.More infoInternet/intranet
- Collier, R. J. (2012). The new Temperature Humidity Index. Western Dairy Management Conference. Reno, Nevada.
- Collier, R. J. (2012). Unraveling the Specifics of Nutrient Partitioning: A Historical Perspective of Dale E. Bauman and the Concept of Homeorhesis. 2011 Cornell Nutrition Conference. Ithaca, NY.
- Collier, R. J. (2012, May). Southern Great Plains Dairy Consortium Course on Large Herd Dairy Management. Clovis, New Mexico.
- Collier, R. J. (2012, September). Dairying in an Era of Global Warming. Erasmus Mundus Food For Life Program. Copenhagen, Denmark: University of Copenhagen.
- Collier, R. J. (2011). Metabolic Health of the Bovine Mother. 62nd Annual Meeting European Animal Production Conference. Stavanger, Norway.
- Collier, R. J. (2011). New Concepts on Impact of Thermal Stress on Lactation in Dairy Cows. Madison, Wisconsin: University of Wisconsin, Dairy Science Department Seminar.
- Collier, R. J. (2011). Serotonin as a Homeostatic Regulator of Bovine Lactation. 7th International Congress on Farm Animal Endocrinology. Berne, Switzerland.More infoInternet/intranet
- Collier, R. J. (2011). The new Temperature Humidity Index. Western Dairy Management Conference. Reno, Nevada.
- Collier, R. J. (2011). Unraveling the Specifics of Nutrient Partitioning: A Historical Perspective of Dale E. Bauman and the Concept of Homeorhesis. 2011 Cornell Nutrition Conference. Ithaca, NY.
- Collier, R. J. (2011, August). Serotonin as a Homeostatic Regulator of Bovine Lactation. 7th International Congress on Farm Animal Endocrinology. Berne, Switzerland.
- Collier, R. J. (2011, December). New Concepts on Impact of Thermal Stress on Lactation in Dairy Cows. Dairy Science Department Seminar. Madison, Wisconsin: University of Wisconsin.
- Collier, R. J. (2011, March). The New Temperature Humidity Index. Western Dairy Management Conference.
- Collier, R. J. (2011, May). Large Herd Dairy Management. Southern Great Plains Dairy Consortium Course. Clovis, NM.
- Collier, R. J. (2011, May). Southern Great Plains Dairy Consortium Course on Large Herd Dairy Management. Clovis, New Mexico.
- Collier, R. J. (2011, October). Unraveling the Specifics of Nutrient Partitioning: A Historical Perspective of Dale E.... 2011 Cornell Nutrition Conference. Ithaca, NY.
- Collier, R. J. (2011, September). Dairying in an Era of Global Warming. Eramus Mundus Food for Life Program. Copenhagen: University of Copenhagen.
- Collier, R. J. (2011, September). Dairying in an Era of Global Warming. Erasmus Mundus Food For Life Program. Copenhagen, Denmark: University of Copenhagen.
- Collier, R. J. (2011, September). Metabolic Health of the Bovine Mother. 62nd Annual Meeting European animal Production Conference. Stavanger, Norway.
- Burger, C. A., Collier, J. L., & Collier, R. J. (2015, July). Characterization of prolactin and adrenergic and serotonergic receptors in bovine apocrine sweat glands.. Joint American Society of Animal Science and American Dairy Science Association Meeting. Orlando, florida: American Society of Animal Science and American Dairy Science Association.More infoApocrine sweat glands are involved in thermoregulation via evaporative heat loss in the bovine and are most active at temperatures above thermoneutral. We have previously shown that serotonin (5-HT) receptors 5-HT 1b, 2b, 4, and 7 are found in whole skin, apocrine sweat glands, and epithelial cells, while 5-HT 2a is present in whole skin and epithelial cells. It has been shown that prolactin (PRL) plays a role in lactational homeostasis, and since mammary glands are modified apocrine sweat glands, we hypothesized that PRL receptors would be present in these sweat glands. Additionally, we looked at adrenergic (ADR) receptors, as epinephrine is known to influence sweating response. The present study was conducted to determine if the 5-HT, PRL, and ADR systems are involved in thermoregulation by looking at the cDNA expression through conventional PCR of receptors in bovine whole skin, apocrine sweat glands, and epithelial cells. For the 5-HT system, brain was used as a control and additional isoforms classified were 5-HT 1a, 1d, 1f, 5a, and 6. We identified isoforms 5-HT 1d, 1f, and 5a in whole skin, isolated apocrine sweat glands, and epithelial cells, while 5-HT 1a is present in whole skin and epithelial cells, and 5-HT6 is present in whole skin and isolated apocrine sweat glands. For the PRL system, bovine mammary epithelial cells (BMEC) were the control and two isoforms were identified: PRL receptor long (PRLr-L) and PRL receptor short (PRLr-S) which differ in their intracellular domain length and sequence. We found that PRLr-S is in whole skin, apocrine sweat glands, and epithelial cells, while PRLr-L is found in only whole skin. For the ADR receptors, BMEC and liver were used as control, and we found α1 ADR 1a, α2 ADR, β1 ADR, and β2 ADR receptors in whole skin, apocrine sweat glands, and epithelial cells. α1 ADR 1b was only present in BMEC and liver, while α1 ADR 1d was only in BMECs. The presence of these receptors in the apocrine glands and epithelial cells indicates that the 5-HT, PRL, and ADR systems are involved in regulation of apocrine sweat gland function.
- Sanchez, N. B., Carroll, J. A., Broadway, P. R., Ortiz, X. A., McBride, M. L., Collier, J. L., Chapman, J. L., McLean, D., & Collier, R. J. (2015, july). OmniGen-AF alters rectal temperature (RT) and leukocyte profiles in dairy cows exposed to heat stress (HS) following acute activation of the stress axis.. joint ASAS/ADSA Meetings. Orlando, florida: American Society of Animal Science and American Dairy Science Association.More infoDifferences in the response of OmniGen-AF (OG) supplemented dairy cows to a corticotropin releasing hormone (CRH) and vasopressin (VP) or an adrenocorticotropic hormone (ACTH) challenge when housed at different temperature-humidity indices (THI) was studied. Holstein cows (n=12; 162±1 DIM) were balanced by milk yield, BW and Days in MIlk into 1 of 2 trts: 1) OmniGen-AF, supplemented with OG at 4.54 g/kg BW for 70d; or 2) Control (CON), no supplement. Cows were moved to individual tie stalls in 1 of 2 temperature controlled chambers on d 51 and fitted with indwelling RT devices and jugular catheters on d 52_. Initially THI was cycling at thermoneutrality [TN; THI72 for 12h/d) for _10d. Cows were challenged with CRH (0.3 µg/kg) and VP (1 µg/kg) at 1000h on d4 of TN and d1 of HS, and with ACTH (0.1 IU/kg) at 1000h on d5 of TN and d2 of HS. Blood samples were collected from -2 to 8h at 30-min intervals relative to each challenge and analyzed for complete blood cell counts. There was a THI x time interaction (P≤0.01) for RT such that RT was greater during HS than TN (2 to 9h, and at 11h for CRHVP and 4 to 9h and 11 to 13h for ACTH). Also, RT was greater (P≤0.02) in OG than CON cows regardless of challenge. Total white blood cells (WBC) and neutrophils (NEUT) increased (P
- Collier, R. J. (2010, Fall). Effects of heat stress and Niashure (NI) supplementation on winter acclimated lactating cattle. Not Provided in APROL.
- Collier, R. J., & Bilby, T. (2015. Make heat abatement a priority for better milk production. Progressive Dairymen.More infoLay publication on reducing impact of heat stress on dairy herds
- Macko, A. R., Limesand, S., & Collier, R. J. (2015, july). Effect of heat stress during pregnancy on intact and adrenal de-medullated fewtuses: Placental,fetal and mammary development in ewes.. http://www.jtmtg.org/JAM/2015/abstracts.aspMore infoIt is well established that heat stress during mid- and late-gestation induces intrauterine growth retardation (IUGR) and decreased milk yield in the subsequent lactation in cattle and sheep. We hypothesized that elevated fetal adrenal norepinephrine (NE) secretion contributes to impaired mammary development in heat stressed pregnant ewes. Pregnant ewes were assigned to one of four treatment groups that were a combination of control (C) or hyperthermia-induced IUGR (I) and surgical sham (S) or bilateral fetal adrenal demedullation (D) at 98 days gestational age (dGA; term = 148 dGA)(n = 4 CS, 4 CD, 6 IS, and 4 ID fetuses). At 134 dGA, fetal plasma NE was measured, animals were euthanized, and fetal and placental weights obtained. Ewes’ mammary glands were collected, weighed and prepared for analyses of DNA content, and histological evaluation to quantify the numbers of alveolar units per microscopic field and mammary epithelial cells per alveolus. Data was analyzed by Proc Mixed ANOVA, SAS 9.3. In the IS group, fetal plasma NE was 4-fold higher (P
- Allen, J. D., Anderson, S. D., Collier, R. J., & Smith, J. F. (2013, Feb). Managing heat stress and its impact on cow behavior.. Proc. Western Large Herd Management Conf. Proc. pp. 150-162..
- Allen, J. D., Anderson, S. D., Collier, R. J., & Smith, J. F. (2013, February). Managing heat stress and its impact on cow behavior.. Proc. Southwest Nutr. Mgmt. Conf. pp. 68-79..
- Allen, J. D., Hall, L. D., Zie, G., Collier, R. J., Baumgard, L. H., & Rhoads, R. P. (2013, July). . Effects of heat stress and plane of nutrition on fecal composition of lactating dairy cows.. J. Anim Sci. 91:E-Suppl 2. P.261..
- Collier, R. J. (2013, July). Environmental heat stress modulates thyroid status and its response to repeated endotoxin (LPS) challenge in steers.. J. Anim Sci. 91: Supple 2. P. 481 (Abstract)..
- Collier, R. J., Anderson, S. D., Allen, J. D., & Smith, J. F. (2013, July). Effects of an adjustable fan and mister cooling system with different motor size and water output on core body temperature (CBT) of lactating dairy cows.. J. Dairy Sci. 96:E Supple I. p. 51..
- Collier, R. J., Hall, L. W., & Ortiz, X. (2013, December). Facility modifications to reduce heat stress. Proc. Dairy Heat Stress Road Show. Okeechobee, Fl and Camuy, Puerto Rico. Funded by Ag AFRI Competitive Grant 2010-85122-20623. pp. 12-23..
- Hall, L. W., & Collier, R. J. (2013, Feb). Use of probiotics in dairy rations during heat stress. Proc. Southwest Nutr. Mgmt. Conf. pp. 153-163..
- Hall, L. W., Anderson, S. D., Rivera, F. A., Vilar, F., Chapman, J. D., Long, N. M., & Collier, R. J. (2013, July). Evaluation of OmniGen-AF in heat-stressed Holstein cows in lactation. J. Dairy Sci 96:E-Suppl I. p. 448. (abstract).
- Collier, R. J. (2011, October). Invited Speaker. Argentine Animal Production Conference.
- Collier, R. J., Collier, J., Hernandez, L., & Horseman, N. (2011, July). Effect of intramammary infusions of Fluoxetine (FLX) and 5-hydroxytryptophan (5-HTP) on milk secretion rate and composition in lactating Holstein cows at dry-off. Joint Animal and Dairy Science Meetings.
- Collier, R. J., Hernandez, L., & Horseman, N. (2011, July). Acute Fluoxetine administration accelerates mouse mammary gland involution. Joint animal and Dairy Science Meetings.
- Collier, R. J., Olea, W., Parlow, A., & Hadsell, D. (2011, July). Improved lactation persistence and altered milk composition in growth hormone-treated mice is not linked to dramatic changes in mammary mitochondrial biogenesis or the degree of mTOR or AMP kinase phosphorylation. Joint animal and Dairy Science Meetings.
- Collier, R. J., Rungruang, S., Rhoads, R., Baumgard, L., DeVeth, M., & Collier, J. (2011, July). Effects of heat stress and Niashure (NI) supplementation on winter acclimated lactating cattle. Joint Animal and Dairy Science Meetings - Multiple Abstracts.