青年奶牛同期发情和同期排卵－定时输精试验

试验旨在研究同期发情和同期排卵－定时输精技术在青年奶牛中的应用。选择1046头澳大利亚进口荷斯坦青年奶牛,随机分为两组:一组自然发情人工授精配种(对照组);另一组采用前列腺素F_2α(PGF_2α)诱导母牛发情或按照同期排卵－定时输精程序(Ovsynch或Ovsynch+CIDR法)处理母牛后人工授精配种(试验组),统计同期发情率、不返情率、第一次人工授精妊娠率和21d妊娠率等繁殖指标。结果表明,试验组青年奶牛人工授精后不返情率和第一次人工授精妊娠率与对照组间无显著差异(P>0.05),但21d妊娠率显著高于对照组(53.1%和35.3%,P<0.05)。试验组中,1次PG法、间隔7d2次PG法和间隔11d2次PG法的同期发情率分别为76.1%、81.7%和84.6%,差异均不显著(P>0.05);同期排卵－定时输精组中,Ovsynch法(GPG)和Ovsynch+CIDR法(GPG+CIDR)的不返情率、第一次人工授精妊娠率和21d妊娠率间无显著差异(P>0.05)。不同输精人员可显著影响青年奶牛的第一次人工授精妊娠率(P<0.05),而不同公牛常规冷冻精液对青年奶牛第一次人工授精妊娠率无显著影响(P>0.05)。同期发情及同期排卵－定时输精技术可使青年奶牛集中发情,提高参配率,从而提高21d妊娠率,有效加快青年奶牛人工授精效率,降低饲养成本。

The Effects of Estrus Synchronization and Ovsynch-timed Artificial Insemination on Dairy Heifers

This experiment was designed to investigate the application of estrus synchronization and Ovsynch-timed artificial insemination(TAI) in dairy heifers.1 046 Holstein dairy heifers imported from Australia were randomly assigned into two groups.The heifers in the control group were checked for spontaneous heat, and the heifers in experimental group were treated by prostaglandin F_2α(PGF_2α) to induce heat synchronization or treated by different TAI programs (Ovsynch or Ovsynch+CIDR program).The estrus synchronization rate, 24 d-non-return rate after AI, first AI conception rate and 21-day pregnancy rate were analyzed in each group.The results showed that there was no significant difference in 24 d-non-return rate and the first AI conception rate between the experimental group heifers and control group (P>0.05), but the 21 d pregnancy rate of the experimental group was significantly higher than that of control group (53.1% and 35.3%;P<0.05).There was no significant difference of the estrus synchronization rate between different PG treatments (PG, PG-7-PG and PG-11-PG) (76.1%, 81.7% and 84.6%;P>0.05).There was no significant difference in 24 d-non-return rate, the first AI conception rate and 21 d pregnancy rate in Ovsynch (GPG) and Ovsynch+CIDR (GPG+CIDR) programs (P>0.05).The first AI conception rate of dairy heifers was significantly affected by different AI technicians (P<0.05), but there was no effect of frozen semen from different bulls on the first AI conception rate (P>0.05).Estrus synchronization and TAI programs could increase the submission rate as a result increasing the 21 d pregnancy rate by inducing dairy heifers to heat in a short time, and accelerate the efficiency of AI to reduce the feeding cost effectively.