Pancarci S M, Jordan E R, Risco C A, Schouten M J, Lopes F L, Moreira F, Thatcher W W
Department of Animal Sciences, College of Veterinary Medicine, University of Florida, Gainesville 32611, USA.
J Dairy Sci. 2002 Jan;85(1):122-31. doi: 10.3168/jds.S0022-0302(02)74060-5.
Experiment 1 evaluated pregnancy rates when estradiol cypionate (ECP) was used to induce ovulation as part of a timed artificial insemination (TAI) protocol in comparison to Ovsynch for lactating dairy cows in Florida (n = 371) and Texas (n = 321). Cows were presynchronized with two injections of PGF2, (25 mg, im) given 14 d apart with TAI protocols beginning 14 d after the second injection of PGF20. The TAI protocols consisted of an injection of GnRH (100 microg, im) followed by PGF2alpha 7 d later. Then, cows either received an injection of GnRH (Treatment I, Ovsynch) at 48 h after PGF2alpha and inseminated 16 to 24 h later or received an injection of ECP (1 mg, i.m.) at 24 h after PGF2alpha, (Treatment II; Heatsynch) and inseminated 48 h later. In Florida, pregnancy rates after TAI were 37.1 +/- 5.8% for Ovsynch compared with 35.1 +/- 5.0% for Heatsynch. In Texas, pregnancy rates were 28.2 +/- 3.6% for Ovsynch and 29.0 +/- 3.5% for Heatsynch. Overall pregnancy rates did not differ between Ovsynch and Heatsynch treatments. In Experiment 2, estrus and ovulation times were determined in lactating dairy cows submitted to the Heatsynch protocol. Frequencies of detected estrus and ovulation after ECP were 75.7% (28/37) and 86.5% (32/37), respectively. Mean intervals to ovulation were 55.4 +/- 2.7 h (n = 32) after ECP and 27.5 +/- 1.1 h (n = 27) after onset of estrus. Estrus occurred at 29.0 +/- 1.8 h (n = 28) after ECP. It is recommended that any cow detected in estrus by 24 h after ECP injection be inseminated at 24 h and all remaining cows be inseminated at 48 h because 75% (n = 24/32) of the ovulations occurred between > or = 48 h to < or = 72 h after ECP. Synchronization of ovulation and subsequent fertility indicated that estradiol cypionate could be used to induce ovulation for successful timed insemination.
实验1评估了在佛罗里达州（n = 371头）和得克萨斯州（n = 321头）泌乳奶牛中，将环丙孕酮（ECP）用于诱导排卵作为定时人工授精（TAI）方案的一部分时的妊娠率，并与Ovsynch方案进行了比较。奶牛先用两次间隔14天注射的PGF2α（25毫克，肌肉注射）进行预同步处理，TAI方案在第二次注射PGF2α后14天开始。TAI方案包括注射促性腺激素释放激素（GnRH，100微克，肌肉注射），7天后再注射PGF2α。然后，奶牛在注射PGF2α后48小时接受一次GnRH注射（处理I，Ovsynch方案），并在16至24小时后进行人工授精，或者在注射PGF2α后24小时接受一次ECP注射（1毫克，肌肉注射，处理II；Heatsynch方案），并在48小时后进行人工授精。在佛罗里达州，Ovsynch方案TAI后的妊娠率为37.1%±5.8%，而Heatsynch方案为35.1%±5.0%。在得克萨斯州，Ovsynch方案的妊娠率为28.2%±3.6%，Heatsynch方案为29.0%±3.5%。Ovsynch方案和Heatsynch方案的总体妊娠率没有差异。在实验2中，对接受Heatsynch方案的泌乳奶牛的发情和排卵时间进行了测定。注射ECP后检测到的发情和排卵频率分别为75.7%（28/37）和86.5%（32/37）。注射ECP后到排卵的平均间隔时间为55.4±2.7小时（n = 32），发情开始后为27.5±1.1小时（n = 27）。发情发生在注射ECP后29.0±1.8小时（n = 28）。建议在注射ECP后24小时内检测到发情的任何奶牛在24小时进行人工授精，其余所有奶牛在48小时进行人工授精，因为75%（n = 24/32）的排卵发生在注射ECP后≥48小时至≤72小时之间。排卵同步及随后的繁殖力表明，环丙孕酮可用于诱导排卵以成功进行定时人工授精。
