Effects of Controlled Heat Stress on Ovarian Function of Dairy Cattle. 1. Lactating Cows

¹ Department of Animal Sciences, Department of Veterinary Medicine and Surgery, University of Missouri, Columbia 65211

The objective of this experiment was to determine the effects of controlled heat stress on ovarian function of lactating dairy cows. Estrus was synchronized (estrus = d 0), and cows were randomly assigned to either heat stress ( n = 11; 29°C, 60% relative humidity) or thermoneutral ( n = 11; 19°C, 60% relative humidity) treatment. For cows undergoing heat stress, ambient temperature (19°C) was increased from d 11 to 13 of the estrous cycle (3.3°C/d increase) and remained at 29°C until d 21. Beginning on d 11, the growth and regression of ovarian follicles and corpora lutea were measured by using ultrasonography. Blood was collected daily by coccygeal venipuncture for measurement of serum concentrations of progesterone and estradiol. The second wave dominant follicle was more likely to ovulate in cows in the thermoneutral treatment than in cows undergoing heat stress (91 vs. 18% ovulation, respectively). Patterns of follicular growth in cows under-going heat stress were associated with decreased serum estradiol from d 11 to 21 and on the day of luteolysis. The average day of luteolysis was delayed by 9 d in heat-stressed cows. Conclusions were that follicular growth and development and luteolytic mechanisms were compromised in heat-stressed cows; as a result, luteolysis was delayed, and second wave dominant follicles did not ovulate.

Key Words: heat stress • hyperthermia • ovary • cow

Submitted on August 28, 1997
Accepted on March 23, 1998

This article has been cited by other articles:

				S. Dikmen, E. Alava, E. Pontes, J. M. Fear, B. Y. Dikmen, T. A. Olson, and P. J. Hansen Differences in Thermoregulatory Ability Between Slick-Haired and Wild-Type Lactating Holstein Cows in Response to Acute Heat Stress J Dairy Sci, September 1, 2008; 91(9): 3395 - 3402. [Abstract] [Full Text] [PDF]

				D. Z. Caraviello, K. A. Weigel, M. Craven, D. Gianola, N. B. Cook, K. V. Nordlund, P. M. Fricke, and M. C. Wiltbank Analysis of Reproductive Performance of Lactating Cows on Large Dairy Farms Using Machine Learning Algorithms J Dairy Sci, December 1, 2006; 89(12): 4703 - 4722. [Abstract] [Full Text] [PDF]

				P. W. Parodi Dairy Product Consumption and the Risk of Breast Cancer J. Am. Coll. Nutr., December 1, 2005; 24(suppl_6): 556S - 568S. [Abstract] [Full Text] [PDF]

				L. J. Spicer Effects of Estradiol on Bovine Thecal Cell Function In Vitro: Dependence on Insulin and Gonadotropins J Dairy Sci, July 1, 2005; 88(7): 2412 - 2421. [Abstract] [Full Text] [PDF]

				M Ozawa, D Tabayashi, T A Latief, T Shimizu, I Oshima, and Y Kanai Alterations in follicular dynamics and steroidogenic abilities induced by heat stress during follicular recruitment in goats Reproduction, May 1, 2005; 129(5): 621 - 630. [Abstract] [Full Text] [PDF]

				T. Shimizu, I. Ohshima, M. Ozawa, S. Takahashi, A. Tajima, M. Shiota, H. Miyazaki, and Y. Kanai Heat stress diminishes gonadotropin receptor expression and enhances susceptibility to apoptosis of rat granulosa cells Reproduction, April 1, 2005; 129(4): 463 - 472. [Abstract] [Full Text] [PDF]

				R. Sartori, J. M. Haughian, R. D. Shaver, G. J. M. Rosa, and M. C. Wiltbank Comparison of Ovarian Function and Circulating Steroids in Estrous Cycles of Holstein Heifers and Lactating Cows J Dairy Sci, April 1, 2004; 87(4): 905 - 920. [Abstract] [Full Text] [PDF]

				N. R. St-Pierre, B. Cobanov, and G. Schnitkey Economic Losses from Heat Stress by US Livestock Industries J Dairy Sci, July 1, 2003; 86(13_suppl): E52 - 77. [Abstract] [Full Text] [PDF]

				E. R. Jordan Effects of Heat Stress on Reproduction J Dairy Sci, July 1, 2003; 86(13_suppl): E104 - 114. [Abstract] [Full Text] [PDF]

				R. Sartori, G. J. M. Rosa, and M. C. Wiltbank Ovarian Structures and Circulating Steroids in Heifers and Lactating Cows in Summer and Lactating and Dry Cows in Winter J Dairy Sci, November 1, 2002; 85(11): 2813 - 2822. [Abstract] [Full Text] [PDF]

				O. Ravagnolo and I. Misztal Effect of Heat Stress on Nonreturn Rate in Holsteins: Fixed-Model Analyses J Dairy Sci, November 1, 2002; 85(11): 3101 - 3106. [Abstract] [Full Text] [PDF]

				J.M. Burke, D.E. Spiers, F.N. Kojima, G.A. Perry, B.E. Salfen, S.L. Wood, D.J. Patterson, M.F. Smith, M.C. Lucy, W.G. Jackson, et al. Interaction of Endophyte-Infected Fescue and Heat Stress on Ovarian Function in the Beef Heifer Biol Reprod, July 1, 2001; 65(1): 260 - 268. [Abstract] [Full Text] [PDF]