Elzo M A, Wakeman D L
Animal Science Department, University of Florida, Gainesville 32611, USA.
J Anim Sci. 1998 May;76(5):1290-302. doi: 10.2527/1998.7651290x.
Estimates of covariances and sire expected progeny differences of additive and nonadditive direct and maternal genetic effects for birth and weaning weights were obtained using records from 1,581 straightbred and crossbred calves from the Angus-Brahman multibreed herd at the University of Florida. Covariances were estimated by Restricted Maximum Likelihood, using a Generalized Expectation-Maximization algorithm applied to multibreed populations. Estimates of heritabilities and additive genetic correlations for straightbred and crossbred groups were within the ranges of values found in the literature for these traits. Maximum values of interactibilities (ratios of nonadditive genetic variances to phenotypic variances) and nonadditive correlations were somewhat smaller than heritabilities and additive genetic correlations. Sire additive and total direct and maternal genetic predictions for birth and weaning weight tended to increase with the fraction of Brahman alleles, whereas nonadditive direct and maternal genetic predictions were similar for sires of all Angus and Brahman fractions. These results showed that it is feasible to evaluate sires for additive and nonadditive genetic effects in a structured multibreed population. Data from purebred breeders and commercial producers will be needed to accomplish the same goal at a national level.
利用佛罗里达大学安格斯 - 婆罗门多品种牛群中1581头纯种和杂交犊牛的记录，获得了出生重和断奶重的加性和非加性直接及母体遗传效应的协方差估计值以及父本预期后代差异。协方差采用限制最大似然法估计，运用广义期望最大化算法应用于多品种群体。纯种和杂交群体的遗传力和加性遗传相关估计值在这些性状的文献报道范围内。互作性（非加性遗传方差与表型方差的比值）和非加性相关的最大值略小于遗传力和加性遗传相关。出生重和断奶重的父本加性及总直接和母体遗传预测值往往随着婆罗门等位基因比例的增加而增加，而所有安格斯和婆罗门比例父本的非加性直接和母体遗传预测值相似。这些结果表明，在结构化多品种群体中评估父本的加性和非加性遗传效应是可行的。要在国家层面实现同样的目标，还需要纯种育种者和商业生产者的数据。
