Folman Y, Kaim M, Herz Z, Rosenberg M
J Dairy Sci. 1984 Jan;67(1):153-60. doi: 10.3168/jds.S0022-0302(84)81279-5.
High-yielding dairy cows (199) were allotted to a control group or one of two groups for synchronization of estrus. Synchronization of estrus was accomplished by either insertion of a progesterone-releasing intravaginal device (progesterone coil) for 7 days with .5 mg of the prostaglandin analogue cloprostenol (Estrumate) administered 1 day before removal of the progesterone coil, or by administration of .5 mg of Estrumate followed 13 days later by a progesterone coil inserted for 9 days. Following each estrous synchronization regimen, cows were inseminated during a fixed 6-day period (insemination week). Into one-half of the cows of each treatment group, a second progesterone coil was inserted 12 days following the fixed-time insemination for 9 days. Cows that calved within 21 days were included in a cluster and were treated and inseminated simultaneously at regular 3-wk intervals. Thus, insemination of synchronized cows was during only 6 out of each 21 days. The estrous synchronization regimens were applied so that the first fixed-time insemination for any cow occurred between 59 and 79 days after calving. Control cows were inseminated following estrus, commencing 59 days after calving. Conception rates for cows of groups 1, 2, and 3 were 50, 56, and 51%. Pregnancy rates at 25 days following the fixed-time insemination were 53, 78, and 69%, and at 100 days after calving, 57, 75, and 65%. A system of reproductive management is proposed in which observations for estrous behavior and inseminations are only during 6 days out of each 3 wk.
199头高产奶牛被分配到一个对照组或两个发情同步组中的一组。发情同步通过以下两种方法之一实现：插入一个释放孕酮的阴道内装置（孕酮环）7天，并在取出孕酮环前1天给予0.5毫克前列腺素类似物氯前列醇（氯前列烯醇）；或者给予0.5毫克氯前列烯醇，13天后插入孕酮环9天。在每种发情同步方案之后，奶牛在固定的6天期间（授精周）进行授精。在每个处理组的一半奶牛中，在定时授精12天后插入第二个孕酮环9天。在21天内产犊的奶牛被归为一组，并以3周的固定间隔同时进行处理和授精。因此，同步发情奶牛的授精仅在每21天中的6天进行。应用发情同步方案，使任何奶牛的第一次定时授精发生在产犊后59至79天之间。对照奶牛在产犊后59天开始发情后进行授精。第1、2和3组奶牛的受孕率分别为50%、56%和51%。定时授精后25天的妊娠率分别为53%、78%和69%，产犊后100天的妊娠率分别为57%、75%和65%。提出了一种繁殖管理系统，其中发情行为观察和授精仅在每3周中的6天进行。
