Boligon A A, Albuquerque L G, Mercadante M E Z, Lôbo R B
Faculdade de Ciências Agrárias e Veterinárias, Universidade Estadual Paulista, 14884-900-Jaboticabal, SP, Brazil.
J Anim Sci. 2008 Nov;86(11):2840-4. doi: 10.2527/jas.2007-0823. Epub 2008 May 23.
Records of 18,770 Nelore animals, born from 1975 to 2002, in 8 herds participating in the Nelore Cattle Breeding Program, were analyzed to estimate genetic parameters for mature BW. The mature BW were analyzed as a single BW taken closest to 4.5 yr of age for each cow in the data file, considering BW starting from 2 (W2Y_S), 3 (W3Y_S), or 4 (W4Y_S) yr of age or as repeated records, including all BW starting from 2 (W2Y_R), 3 (W3Y_R), or 4 (W4Y_R) yr of age. The variance components were estimated by restricted maximum likelihood, fitting univariate and bivariate animal models, including weaning weight. The heritability estimates were 0.29, 0.34, 0.36, 0.41, 0.44, and 0.46 for W2Y_S, W3Y_S, W4Y_S, W2Y_R, W3Y_R, and W4Y_R, respectively. The repeatability estimates for W2Y_R, W3Y_R, and W4Y_R were 0.59, 0.64, and 0.72, respectively. Larger accuracy values associated with the EBV were obtained in the repeated records models. The results indicated the bivariate repeated records model as the most appropriate for analyzing mature BW.
对参与内洛尔牛育种计划的8个牛群中1975年至2002年间出生的18770头内洛尔牛的记录进行了分析，以估计成熟体重的遗传参数。成熟体重被分析为数据文件中每头母牛最接近4.5岁时的单一体重，考虑从2岁（W2Y_S）、3岁（W3Y_S）或4岁（W4Y_S）开始的体重，或作为重复记录，包括从2岁（W2Y_R）、3岁（W3Y_R）或4岁（W4Y_R）开始的所有体重。通过限制最大似然法估计方差分量，拟合单变量和双变量动物模型，包括断奶体重。W2Y_S、W3Y_S、W4Y_S、W2Y_R、W3Y_R和W4Y_R的遗传力估计值分别为0.29、0.34、0.36、0.41、0.44和0.46。W2Y_R、W3Y_R和W4Y_R的重复性估计值分别为0.59、0.64和0.72。在重复记录模型中获得了与估计育种值相关的更大准确性值。结果表明，双变量重复记录模型最适合分析成熟体重。
