By slaughtering sows at different time after the onset of estrus,it was shown that the ovulation began about 40 -72 hours after the beginning of estrus in the large Yorkshire breed.

• 通过对大约克母猪在发情不同时间分批屠宰测定表明，大约克母猪排卵时间是在发情开始后48小时左右至72小时之前这一范围。