Abstract：
Reproduction is essential for successful cow-calf and dairy production and the most important economic trait for cow-calf producers. For efficient reproduction to occur in beef herds, cows or heifers must conceive early during the breeding season, maintain the pregnancy, calve unassisted or with very little assistance, rebred in a timely manner and wean a calf every year. In the case of dairy cattle, cows or heifers are expected to become pregnant, maintain the pregnancy, and calve every 12 to 15 months to produce milk. Interruption of that process leads to delay or total loss of production. Although fertile bulls are required to achieve reproduction, they come with potential risk of transmitting disease during breeding.
摘要：
繁殖对于成功的奶牛和奶牛生产至关重要，也是奶牛生产者最重要的经济性状。为了在牛群中有效繁殖，母牛或小母牛必须在繁殖季节早期受孕，保持怀孕，没有帮助或很少有帮助的小牛，及时返补，每年给小牛断奶。就奶牛而言，奶牛或小母牛预计会怀孕，保持怀孕，每12到15个月产奶。该过程的中断导致生产的延迟或全部损失。尽管繁殖需要肥沃的公牛，它们在繁殖过程中具有传播疾病的潜在风险。
