Tippenhauer Christie Marie, Plenio Jan-Lukas, Madureira Augusto, Heuwieser Wolfgang, Borchardt Stefan
Farm Animal Clinic, Division for Ruminants and Camelids, Unit for Reproduction Medicine and Udder Health, School of Veterinary Medicine, Freie Universitaet Berlin, 14163 Berlin, Germany.
Institute for Veterinary Epidemiology and Biostatistics, Freie Universitaet Berlin, 14163 Berlin, Germany.
Animals (Basel). 2023 Sep 22;13(19):2994. doi: 10.3390/ani13192994.
Investigations on the optimum timing of artificial insemination (AI) following automated activity monitoring (AAM) depending on different types of semen in heifers are limited and in part show controversial results. Therefore, the objective of this observational study was to determine the association between the timing of AI using different characteristics of estrus (i.e., the onset, peak, and end of estrus) and pregnancy per AI (P/AI) in Holstein heifers. Heifers were fitted with a neck-mounted AAM system and inseminated with frozen conventional and sexed semen. The pregnancy per AI ( = 4159) from 2858 heifers from six commercial dairy farms in Germany inseminated upon the alert of an AAM system was evaluated. Estrous intensity was classified based on peak activity into low (35 to 89 index value) and high (90 to 100 index value). We detected a quadratic association between the interval from the onset of estrus to AI and P/AI ( = 0.02). The greatest P/AI was observed for heifers inseminated from 9 to 32 h after the onset of estrus. The intervals from the peak of activity to AI and the end of estrus to AI were not associated with P/AI ( ≥ 0.05). Heifers inseminated with frozen conventional semen (50.1%) had a greater P/AI compared with heifers inseminated with frozen sexed semen (43.3%; = 0.03). There were no interactions between the intervals from the onset, peak, or end of estrus to AI or the type of semen and the P/AI ( ≥ 0.05). The pregnancy per AI was not associated with estrous intensity (50.5% for low intensity vs. 53.0% for high intensity; = 0.37). In conclusion, inseminating heifers between 9 and 32 h after the onset of estrus, as detected by the AAM, optimized the P/AI regardless of semen type.
关于根据后备奶牛不同类型精液，在自动活动监测（AAM）后进行人工授精（AI）的最佳时机的研究有限，部分研究结果存在争议。因此，本观察性研究的目的是确定在荷斯坦后备奶牛中，利用不同发情特征（即发情开始、峰值和结束）进行AI的时间与每次AI的妊娠率（P/AI）之间的关联。给后备奶牛佩戴颈部安装的AAM系统，并使用冷冻常规精液和性别分选精液进行授精。对德国六个商业奶牛场的2858头后备奶牛在AAM系统发出警报后进行授精的4159次AI的妊娠情况进行了评估。根据活动峰值将发情强度分为低（指数值35至89）和高（指数值90至100）。我们检测到从发情开始到AI的时间间隔与P/AI之间存在二次关联（P = 0.02）。在发情开始后9至32小时进行授精的后备奶牛的P/AI最高。从活动峰值到AI以及从发情结束到AI的时间间隔与P/AI无关（P≥0.05）。与使用冷冻性别分选精液授精的后备奶牛（43.3%）相比，使用冷冻常规精液授精的后备奶牛（50.1%）的P/AI更高（P = 0.03）。从发情开始、峰值或结束到AI的时间间隔或精液类型与P/AI之间没有相互作用（P≥0.05）。每次AI的妊娠率与发情强度无关（低强度为50.5%，高强度为53.0%；P = 0.37）。总之，根据AAM检测，在发情开始后9至32小时对后备奶牛进行授精，无论精液类型如何，均可优化P/AI。
