Gyawu P, Pope G S
Department of Endocrinology and Animal Physiology, AFRC Institute for Grassland and Animal Production, Hurley, Maidenhead.
Br Vet J. 1990 May-Jun;146(3):194-204. doi: 10.1016/s0007-1935(11)80002-3.
Concentrations of oestradiol-17 beta and progesterone in defatted milk have been used to study the post-partum restoration of ovarian function in 52 autumn-calved dairy cattle. In 32 cows the first preovulatory peaks in oestradiol-17 beta concentration (indicative of imminent ovulation) were less than or equal to 15 days and in 49 cows less than or equal to 49 days post partum. Delay to first ovulation was mainly due, not to failure of ovarian secretion of oestradiol-17 beta at preovulatory level, but to failure of oestradiol-17 beta at this level to exert its normal preovulatory function. Longer intervals to first ovulation were associated with longer intervals from calving to the clearance of placental oestradiol-17 beta, high peak milk yields and high body weight losses, suggesting that in high-yielding dairy cows these factors (themselves inter-related) may be associated with others, which are the immediate cause of the inhibition of the normal, preovulatory function of oestradiol-17 beta. Forty-eight per cent of cows had short, first ovulation cycles. Ovarian function, comprising oestradiol-17 beta secretion at preovulatory level, normal preovulatory function of oestradiol-17 beta and normal corpus luteum progesterone secretion were almost fully restored in this herd by the 49th day post partum.
脱脂乳中雌二醇 - 17β 和孕酮的浓度已被用于研究52头秋季产犊奶牛产后卵巢功能的恢复情况。在32头奶牛中，雌二醇 - 17β 浓度的首个排卵前峰值（表明即将排卵）在产后小于或等于15天，49头奶牛在产后小于或等于49天。首次排卵延迟主要不是由于卵巢分泌的雌二醇 - 17β 未达到排卵前水平，而是由于该水平的雌二醇 - 17β 未能发挥其正常的排卵前功能。首次排卵间隔时间较长与产犊至胎盘雌二醇 - 17β 清除的间隔时间较长、高产奶量峰值和高体重损失有关，这表明在高产奶牛中，这些因素（它们本身相互关联）可能与其他因素有关，而这些因素是抑制雌二醇 - 17β 正常排卵前功能的直接原因。48% 的奶牛首次排卵周期较短。到产后第49天，该牛群的卵巢功能，包括排卵前水平的雌二醇 - 17β 分泌、雌二醇 - 17β 的正常排卵前功能和黄体孕酮的正常分泌，几乎完全恢复。
