Abstract：
Estrous synchronization, coupled with natural service, provides the benefit of female cows conceiving early, but there are an increased number of females expressing estrus in a short period of time. Thus, considerations need to be made for the bull. Select a protocol that will distribute estrus over a longer period of time and ensure bulls pass a breeding soundness examination. Mature bulls (3 years old or older) have increased efficiency in getting cows pregnant compared with younger bulls; therefore, a ratio of 1 mature bull to 25 cows is a good recommendation within an estrous synchronized herd.
摘要：
发情同步，加上自然服务，提供了雌性母牛早期受孕的好处，但是在短时间内表达发情的雌性数量有所增加。因此，需要为公牛考虑。选择一个方案，该方案将在更长的时间内分配发情期，并确保公牛通过繁殖健全性检查。与年轻的公牛相比，成熟的公牛（3岁或3岁以上）在使母牛怀孕方面的效率更高；因此，在发情的同步牛群中，1头成熟公牛与25头母牛的比例是一个很好的建议。
