Estimation of genetic parameters for birth and weaning weights of crossbred cattle among Thai native, Brahman and Charolais population

Abstract

This study was to estimate genetic parameters for birth weight (BW) and weaning weights (WW) ofcrossbred cattle among Thai Native, Brahman and Charolais population. Variance and covariance componentswere estimated using Restricted Maximum Likelihood (REML). Six different univariate models were employed toestimate genetic parameters. Model 1 included fixed effects of sex, contemporary group, breed fractions of animaland dam and random direct additive genetic effects and residual effects. Model 1 was extended to include maternalgenetic effects without (Model 2) or with (Model 3) correlation between direct and maternal genetic effects.Model 4 added maternal permanent environmental effects to Model 2. Model 5 added maternal permanentenvironmental effects to Model 3. Model 6 added maternal permanent environmental effects to Model 1 (only forBW). Results from Models 2, 3 and 6 showed that direct and maternal additive genetic effects and maternalpermanent environmental effects were confounded. Comparing between Models 4 and 5 direct and maternal additivegenetic correlations were not significant for both traits. Estimates of direct heritability were highest in Model 1.From likelihood ratio test, Model 4 was the most appropriate for both traits. The estimates of direct and maternalheritabilities and ratio of variance due to maternal permanent environmental effects of Model 4 for BW were 0.21,0.07 and 0.10, respectively and for WW were 0.23, 0.08 and 0.10, respectively.