Journal of Animal Science, Vol 79, Issue 2 309-316, Copyright © 2001 by American Society of Animal Science

JOURNAL ARTICLE

Effectiveness of GnRH plus prostaglandin F2alpha for estrus synchronization in cattle of Bos indicus breeding

J. W. Lemaster, J. V. Yelich, J. R. Kempfer, J. K. Fullenwider, C. L. Barnett, M. D. Fanning and J. F. Selph
Department of Animal Sciences, University of Florida, Gainesville 32611-0910, USA.

Postpartum and lactating crossbred cows containing a percentage of Bos indicus breeding at three locations were studied to determine the efficacy of GnRH + PGF2alpha combinations for synchronization of estrus and(or) ovulation. Cows were equally distributed to each of three treatments by body condition score at the start of the experiment (d 0). All cows received 100 microg of GnRH on d 0 and 25 mg of PGF2alpha 7 d later. The three insemination protocols included 1) AI 12 h after exhibiting estrus during d 7 to 12 of the experiment (Select-Synch; n = 197); 2) timed-AI + 100 microg of GnRH on d 9 of the experiment (CO-Synch; n = 193); 3) AI 12 h after exhibiting estrus during d 7 to 10 of the experiment. Cows not exhibiting estrus by d 10 were timed-AI and injected with 100 microg of GnRH on d 10 of the experiment (Hybrid-Synch; n = 200). The percentage of cows exhibiting estrus during d 7 to 12 of the experiment was lower (P < 0.05) for CO-Synch (17.6%) cows than for Select-Synch or Hybrid-Synch (45.2 and 33.0%, respectively) cows, which did not differ (P > 0.05). For the Select-Synch and Hybrid-Synch cows that exhibited estrus during d 7 to 10 of the experiment and were artificially inseminated, conception rates were similar across treatments (50.5%). Pregnancy rates were greater (P < 0.01) for CO-Synch and Hybrid-Synch (31.0 and 35.5%, respectively) cows than for Select-Synch (20.8%) cows. A greater (P < 0.01) percentage of cycling cows became pregnant (34.5%) than noncycling cows (25.9%) across all treatments. The CO-Synch and Hybrid-Synch synchronization protocols resulted in greater pregnancy rates compared with the Select-Synch protocol in postpartum and lactating crossbred cows containing a percentage of Bos indicus breeding.

This article has been cited by other articles:

				J. G. Berardinelli, P. S. Joshi, and S. A. Tauck Conception rates to artificial insemination in primiparous, suckled cows exposed to the biostimulatory effect of bulls before and during a gonadotropin-releasing hormone-based estrus synchronization protocol J Anim Sci, March 1, 2007; 85(3): 848 - 852. [Abstract] [Full Text] [PDF]

				J. P. Saldarriaga, D. A. Cooper, J. A. Cartmill, J. F. Zuluaga, R. L. Stanko, and G. L. Williams Ovarian, hormonal, and reproductive events associated with synchronization of ovulation and timed appointment breeding of Bos indicus-influenced cattle using intravaginal progesterone, gonadotropin-releasing hormone, and prostaglandin F2{alpha} J Anim Sci, January 1, 2007; 85(1): 151 - 162. [Abstract] [Full Text] [PDF]

				R. Flores, M. L. Looper, D. L. Kreider, N. M. Post, and C. F. Rosenkrans Jr. Estrous behavior and initiation of estrous cycles in postpartum Brahman-influenced cows after treatment with progesterone and prostaglandin F2{alpha} J Anim Sci, July 1, 2006; 84(7): 1916 - 1925. [Abstract] [Full Text] [PDF]

				E. A. Hiers, C. R. Barthle, MK. V. Dahms, G. E. Portillo, G. A. Bridges, D. O. Rae, W. W. Thatcher, and J. V. Yelich Synchronization of Bos indicusxBos taurus cows for timed artificial insemination using gonadotropin-releasing hormone plus prostaglandin F2{alpha} in combination with melengestrol acetate J Anim Sci, April 1, 2003; 81(4): 830 - 835. [Abstract] [Full Text] [PDF]