Eler J P, Van Vleck L D, Ferraz J B, Lôbo R B
Department of Animal Science, University of Nebraska, Lincoln 68583-0908, USA.
J Anim Sci. 1995 Nov;73(11):3253-8. doi: 10.2527/1995.73113253x.
Estimates of (co)variance components and genetic parameters were obtained for birth, 205-d, and 365-d weight for Nelore cattle in Brazil, using single and multiple-trait animal models. Data were from the Brazilian Zebu Breeders Association (ABCZ). Records of 27,549 calves sired by 587 bulls and raised on pasture in 57 herds were analyzed by restricted maximum likelihood fitting an animal model including direct and maternal genetic and permanent environmental effects. Single and multiple-trait analyses were carried out. Heritability estimates for direct effects were lower than previous values reported for the Nelore breed. The estimates for maternal genetic effects showed that the contribution of this component to the phenotypic variance of birth and weaning weight is not very high but is still present at yearling weight. Correlations between direct and maternal additive genetic effects were negative for all traits analyzed except for yearling weight in the single-trait analysis where the sign was positive but the magnitude was small (+.09). Genetic correlations between weaning and yearling weights were .74 (direct effect) and .84 (maternal effect). Permanent environmental and residual correlations among traits were also obtained.
利用单性状和多性状动物模型，对巴西内洛尔牛的出生重、205日龄体重和365日龄体重的（协）方差分量及遗传参数进行了估计。数据来自巴西瘤牛养殖者协会（ABCZ）。对587头公牛所生并在57个牛群的牧场中饲养的27549头犊牛的记录进行了分析，采用限制最大似然法拟合了一个动物模型，该模型包括直接遗传效应、母体遗传效应和永久环境效应。进行了单性状和多性状分析。直接效应的遗传力估计值低于先前报道的内洛尔品种的值。母体遗传效应的估计表明，该组分对出生体重和断奶体重表型方差的贡献不是很高，但在周岁体重时仍然存在。除了单性状分析中的周岁体重（其符号为正但幅度较小（+.09））外，所有分析性状的直接加性遗传效应和母体加性遗传效应之间的相关性均为负。断奶体重和周岁体重之间的遗传相关性分别为0.74（直接效应）和0.84（母体效应）。还获得了性状之间的永久环境相关性和残差相关性。
