Estimation of genetic variation in the interval from calving to postpartum ovulation of dairy cows
Estimation of genetic variation in the interval from calving to postpartum ovulation of dairy cows
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DOI：
10.3168/jds.s0022-0302(97)76051-x
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发表时间：
1997-06-01
影响因子：
3.5
通讯作者：
Woolliams, JA
中科院分区：
文献类型：
--
作者：
Darwash, AO;Lamming, GE;Woolliams, JA
1975年至1982年，对11个商业牛群和1个实验牛群中的1137头英国黑白花奶牛进行了1737次泌乳，获得了从产犊到产后奶牛黄体活动开始的间隔数据。从产犊到黄体活动开始的时间间隔使用乳汁样品的孕酮浓度来测量，所述乳汁样品从产犊后不久到下一次妊娠的约100 DIM每周收集三次或更多次。使用REML拟合遗传模型，并考虑已知的遗传关系。未转换数据的遗传力和重复性估计值分别为0.28和0.28;对数转换数据的估计值分别为0.21和0.26;考虑倒数后的估计值分别为0.13和0.26。在所有情况下，遗传力均显著不同于0，且在三个尺度中，对数转换的可能性较大。转换的似然系数与偏度系数的大小密切相关，最大似然的幂转换在0.35 ~ 0.30之间，遗传力为0.19。的几何平均间隔为25.6天，变异系数为37%，畜群，年，胎次和季节都有显着影响的间隔后，开始黄体活动。产后间隔随着每胎次增加2.2%[置信区间95%（1.1%，3.0%）]，并显示出季节性变化。在春季产犊的奶牛开始黄体活动的时间比在秋季产犊的奶牛长1.21倍[95%置信区间（1.13，1.29）]。遗传回归PTA的公鹿的牛奶，脂肪和蛋白质产量和脂肪和蛋白质的百分比和国民经济指数进行了使用一个子集的动物在721哺乳期。脂肪百分比的回归为正，但其他与0无显著差异。本研究中遗传力估计值的大小表明，产后至黄体活动开始的间隔可能有助于选择提高生育力的牛，因为已假定较短的间隔与较高的生殖效率相关。
Data on the interval from calving to the commencement of luteal activity of postpartum dairy cows were obtained for 1737 lactations of 1137 British Friesian cows in 11 commercial herds and 1 experimental herd between 1975 and 1982. The interval from calving to commencement of luteal activity was measured using progesterone concentrations of milk samples that were collected three or more times per week from shortly after calving to approximately 100 DIM of the following gestation. Genetic models were fitted using REML and accounting for known genetic relationships. Estimates of heritability and repeatability were 0.28 and 0.28, respectively, for the untransformed data; 0.21 and 0.26, respectively, for log-transformed data; and 0.13 and 0.26, respectively, after reciprocals were considered. In all cases, the heritability was significantly different from 0, and, of three scales, the log transformation had the greater likelihood. The Likelihood of the transformation was closely related to the magnitude of the coefficient of skewness, and the power transformation with maximum likelihood was between 0.35 and 0.30, for which heritability was 0.19. The geometric mean interval was 25.6 d; coefficient of variation was 37%; and herds, years, parity, and season all had significant effects upon the interval to commencement of luteal activity. The postpartum interval grew longer by 2.2% with each parity [confidence interval 95% (1.1%, 3.0%)] and showed seasonal variation. Cows calving during spring took 1.21 times longer to commencement of luteal activity than did cows calving during autumn [95% confidence interval (1.13, 1.29)]. Genetic regression on PTA of the sire for milk, fat, and protein yields and for fat and protein percentages and on a national economic index were carried out using a subset of animals during 721 lactations. The regression was positive for fat percentage, but not significantly different from 0 for others. The magnitude of the heritability estimate in this study indicates that the postpartum interval to commencement of luteal activity may be useful for selecting cattle for improved fertility because shorter intervals have been postulated to be correlated with higher reproductive efficiency.