用约束最大似然法估计多胎动物的遗传力和共同环境效应

Estimates of Heritabilities and Common Environmental Effects of Littermates for Multifoetal Animal by Restricted Maximum Likelihood

本文研究对于多胎动物利用约束最大似然法(REML)估计父畜、父内窝间和剩余误差的方差组分。以猪达到105公斤体重的日龄(D105)和背膘厚度(ABF)为例,把D105和ABF的记录都调整到以105公斤为基础。采用的混合模型包括出生一年一月(BYM)、猪的性别和母猪产次的固定效应,随机效应是父畜、BYM和父畜内的窝及剩余误差。利用REML来估计父畜的方差组分(0 0,BYM和父畜内的窝方差组分和剩余误差。假定这些方差来源内的每个随机效应相互独立和同一分布,即Var=Iσ_s^2,VasIσ_1~2Var(e)=Iσ_e^2;随机效应间不存在协方差,即COV=0,Cov=0,COV=0。遗传力(h^2)和同窝小猪的共同环境效应(C^2)的估值分别按=和=计算。

Components of variance for sire, litter nested within sire andresidual effects were estimated by restricted maximum likelihood(REML)for multifoetal animal. The age in days at 105kg of body weight(D105)and average backfat thickness (ABF) of swine was taken for example.Both D105 and ABF were adjusted to a 105kg basis. A mixed modelincluding the fixed effects of birth-year-month(BYM), sex of the pig andparity of the dam(gilt vs. sow) was used for estimating components ofvariance. Random effects in the model were sire, litter nested withinBYM and sire, and residual error. REML was used to estimate thecomponents of variance for sire , litter nested within BYM and sire, and residual error, with the assumption that each random effect within these sources of variance was distributed independently andidentically, i. e, var(s)=Iσ_s^2 var(I)=Iσ_i^2, var(e)=Iσ_e^2, with no co-variances among the radom effects, i.e. cov=0, coy=0,coy =O.Heritability(h^2) and common envirnmental effect of litter-mates (c^2) were estimated as h^2=respectively.