Genetic parameters for birth weight and weaning weight in Anglo-Nubian, Saanen, Thai native and crossbred goats

Genetic parameters were estimated for birth weight and weaning weight in Anglo-Nubian, Saanen, Thai native and crossbred goat populations maintained at the Yala Livestock Research and Breeding Center. Records on 2,845 kids descended from 54 bucks and 615 does from 1995 to 2005 were included in the analysis. Analyses were carried out using the DFREML algorithm and fitting four different animal models that included or ignored maternal genetic and permanent environmental effects. In Model 1 only the direct genetic effect was fitted. The maternal permanent environmental effect was added in Model 2, while the maternal genetic effect was added in Model 3. In Model 4, the maternal genetic and permanent environmental effects were included from Model 1. The genetic covariance between the direct and maternal effects was included in Models 3 and 4. The estimates of direct heritability increased when the maternal genetic effect was added with the direct and maternal covariance. The estimates of maternal heritability slightly decreased when the maternal permanent environmental effect was added to the model. The direct-maternal genetic correlation estimates were negative, whereas estimates of the maternal permanent environmental variance as a proportion of phenotypic variance were low. The likelihood ratio test showed that Model 4 was the best for birth weight and Model 3 was the best for weaning weight.