Meyer K
Animal Genetics and Breeding Unit, University of New England, Armidale NSW 2351, Australia.
Genet Sel Evol. 2001 Sep-Oct;33(5):487-514. doi: 10.1186/1297-9686-33-5-487.
Records for birth and subsequent, monthly weights until weaning on beef calves of two breeds in a selection experiment were analysed fitting random regression models. Independent variables were orthogonal (Legendre) polynomials of age at weighing in days. Orders of polynomial fit up to 6 were considered. Analyses were carried out fitting sets of random regression coefficients due to animals' direct and maternal, additive genetic and permanent environmental effects, with changes in variances due to temporary environmental effects modelled through a variance function, estimating up to 67 parameters. Results identified similar patterns of variation for both breeds, with maternal effects considerably more important in purebred Polled Herefords than a four-breed synthetic, the so-called Wokalups. Conversely, repeatabilities were higher for the latter. For both breeds, heritabilities decreased after birth, being lowest when maternal effects were most important around 100 days of age. Estimates at birth and weaning were consistent with previous, univariate results.
在一项选择实验中，对两个品种肉用犊牛出生及随后直至断奶的每月体重记录进行了分析，采用随机回归模型拟合。自变量是称重时以天数表示的年龄的正交（勒让德）多项式。考虑了高达6阶的多项式拟合阶数。分析通过拟合由于动物的直接和母体、加性遗传和永久环境效应产生的随机回归系数集进行，通过方差函数对由于临时环境效应导致的方差变化进行建模，估计多达67个参数。结果表明两个品种的变化模式相似，在纯合无角海福特牛中，母体效应比所谓的四品种合成种沃卡卢普斯更为重要。相反，后者的重复力更高。对于两个品种，出生后的遗传力均下降，在约100日龄母体效应最为重要时最低。出生时和断奶时的估计值与之前的单变量结果一致。
