摘要
牦牛发情集中在7月中旬至9月下旬。发情周期平均20.95±5.13d。发情持续时间在24h以内的占69%超过1d的占31%最长可达96h。发情率为66.7%(n=225),其中空怀牛和带犊牛分别为92.1%和50%。未带犊牛发情期17-β雌二醇平均为231±100pg/mL,黄体期孕酮平均为0.43±0.07ng/mL。每日挤乳1次的带犊牛,孕酮及17-β二醇分别为0.26±0.08ng/mL和61±26.0pg/mL。
Estrus time of yak mostly occurred in July to Septem ber, and estrus cyde ave-rages 20.95±5.13 d, and estrus rate of theseyak (n=225) is 66.7%, in which those of bar-ren and suckler yak are 92.1% and 50%, respectively. As far as duration of estrus, shortest ones are 12 and longest are 96h, and percentage of estrus, within 24 h and over one day, are 69% and 31%, respectively. During the estrus, the mean value of 17-β-oestradiol of barren yak is 231±100pg/mL, while in the luteal phase the progesterone is 0.43±0.07ng/mL. In the sucklers that were milked once per day, the levels of progesterone and 17-β-oestradiol are 0.26±0.08ng/mL(n=9) and 61.0±26.0pg/mL (n=12), respectively.
