Nebel R L, Dransfield M G, Jobst S M, Bame J H
Department of Dairy Science, Virginia Polytechnic Institute and State University, Blacksburg 24061-0315, USA.
Anim Reprod Sci. 2000 Jul 2;60-61:713-23. doi: 10.1016/s0378-4320(00)00090-7.
For the majority of dairy herds where artificial insemination (AI) is practiced, the limiting factor toward obtaining efficient reproductive performance is the failure to detect oestrus in a timely and accurate manner. Periodic visual observation has been the dominant method used to identify cows in oestrus. New approaches are being developed to provide automated systems of detection of oestrus using electronic technology. The goal of an oestrus detection program should be to identify oestrus positively and accurately in all cycling animals and consequently to identify animals not cycling. The ultimate goal should be to predict the time of ovulation, thus allowing for insemination that will maximize the opportunity for conception. Unfortunately, most studies designed to evaluate the optimal time of AI generally contained two technical deficiencies: inadequate numbers of cows for valid statistical comparisons and inaccurate knowledge of the onset of oestrus because of low frequency of visual observations and/or efficiency of methods used for the detection of oestrus. Studies using pedometry and a pressure sensing radiotelemetric system will be reviewed as each have independently obtained an optimal time of AI of 5 to 17 h after either the increase in locomotive activity or following the first standing event associated with the onset of oestrus.
对于大多数采用人工授精（AI）的奶牛群而言，实现高效繁殖性能的限制因素在于未能及时、准确地检测到发情。定期的目视观察一直是用于识别发情母牛的主要方法。目前正在开发新方法，以利用电子技术提供发情自动检测系统。发情检测程序的目标应该是在所有发情周期的动物中准确无误地识别出发情，并进而识别出不发情的动物。最终目标应该是预测排卵时间，从而进行授精，以最大限度地增加受孕机会。不幸的是，大多数旨在评估最佳人工授精时间的研究通常存在两个技术缺陷：用于有效统计比较的奶牛数量不足，以及由于目视观察频率低和/或用于发情检测的方法效率低下，对发情开始时间的了解不准确。将对使用计步器和压力感应无线电遥测系统的研究进行综述，因为每项研究都独立得出了在运动活动增加后或与发情开始相关的第一次站立事件之后5至17小时的最佳人工授精时间。
