1Animal Genetics and Breeding Division, Central Sheep and Wool Research Institute, Avikanagar-304501, via Jaipur, Rajasthan, India.
Animal. 2010 Mar;4(3):425-31. doi: 10.1017/S1751731109991157.
(Co)variance components and genetic parameters of weight at birth (BWT), weaning (3WT), 6, 9 and 12 months of age (6WT, 9WT and 12WT, respectively) and first greasy fleece weight (GFW) of Bharat Merino sheep, maintained at Central Sheep and Wool Research Institute, Avikanagar, Rajasthan, India, were estimated by restricted maximum likelihood, fitting six animal models with various combinations of direct and maternal effects. Data were collected over a period of 10 years (1998 to 2007). A log-likelihood ratio test was used to select the most appropriate univariate model for each trait, which was subsequently used in bivariate analysis. Heritability estimates for BWT, 3WT, 6WT, 9WT and 12WT and first GFW were 0.05 ± 0.03, 0.04 ± 0.02, 0.00, 0.03 ± 0.03, 0.09 ± 0.05 and 0.05 ± 0.03, respectively. There was no evidence for the maternal genetic effect on the traits under study. Maternal permanent environmental effect contributed 19% for BWT and 6% to 11% from 3WT to 9WT and 11% for first GFW. Maternal permanent environmental effect on the post-3WT was a carryover effect of maternal influences during pre-weaning age. A low rate of genetic progress seems possible in the flock through selection. Direct genetic correlations between body weight traits were positive and ranged from 0.36 between BWT and 6WT to 0.94 between 3WT and 6WT and between 6WT and 12WT. Genetic correlations of 3WT with 6WT, 9WT and 12WT were high and positive (0.94, 0.93 and 0.93, respectively), suggesting that genetic gain in post-3WT will be maintained if selection age is reduced to 3 months. The genetic correlations of GFW with live weights were 0.01, 0.16, 0.18, 0.40 and 0.32 for BWT, 3WT, 6WT, 9WT and 12WT, respectively. Correlations of permanent environmental effects of the dam across different traits were high and positive for all the traits (0.45 to 0.98).
在印度拉贾斯坦邦阿维坎加尔的中央绵羊和羊毛研究所，对 Bharat Merino 绵羊的初生重（BWT）、断奶重（3WT）、6、9 和 12 月龄体重（6WT、9WT 和 12WT）和首次油腻羊毛重（GFW）进行了（共）方差组分和遗传参数估计，这些数据通过限制最大似然法获得，使用了六种不同直接和母体效应组合的动物模型。数据收集时间为 10 年（1998 年至 2007 年）。使用对数似然比检验来选择每个性状的最合适的单变量模型，然后在双变量分析中使用该模型。BWT、3WT、6WT、9WT 和 12WT 和首次 GFW 的遗传力估计值分别为 0.05 ± 0.03、0.04 ± 0.02、0.00、0.03 ± 0.03、0.09 ± 0.05 和 0.05 ± 0.03。研究性状没有母体遗传效应的证据。母体永久环境效应对 BWT 的贡献率为 19%，对 3WT 至 9WT 的贡献率为 6%至 11%，对首次 GFW 的贡献率为 11%。3WT 之后的母体永久环境效应是哺乳期前母体影响的延续效应。通过选择，该群体中似乎可以实现较低的遗传进展速度。体重性状之间的直接遗传相关性为正，范围从 BWT 和 6WT 之间的 0.36 到 3WT 和 6WT 之间的 0.94 和 6WT 和 12WT 之间的 0.94。3WT 与 6WT、9WT 和 12WT 的遗传相关性很高且为正（分别为 0.94、0.93 和 0.93），这表明如果选择年龄降低到 3 个月，那么在 3 周龄后进行选择将会保持遗传增益。GFW 与活重的遗传相关性分别为 0.01、0.16、0.18、0.40 和 0.32，对应的是 BWT、3WT、6WT、9WT 和 12WT。所有性状的母体永久环境效应之间的相关性均很高且为正（0.45 至 0.98）。
