Genetic parameter estimates for weaning weight and Kleiber ratio in goats

Abstract

The research was conducted to evaluate the factors affecting on weaning weight (WW) and Kleiber ratio (KR) and toestimate genetic parameters for two traits in goats. The fixed factors affecting both traits indicated that year-season of birth,sex, birth type and regression of the Thai Native (TN), Boer (BO) and Saanen (SA) influenced on WW and KR (P<0.05). Malesin this population were heavier (P<0.05) than females. Weaning weights and KR of single kid were significantly higher (P<0.05) than other birth rearing types. Bivariate analysis of three models (Model 1: without maternal genetic effect, Model 2:with maternal genetic effect and am = 0, and Model 3: with maternal genetic effect and am  0) were used to estimate geneticparameters for this research. Estimated direct heritabilities from all models were 0.26 to 0.38 for WW, and 0.22 to 0.35 for KR.Estimated maternal heritabilities from Model 2 and 3 were 0.09 and 0.12 for WW and 0.08 and 0.11 for KR, respectively. Thedirect genetic and phenotypic correlations between WW and KR were positive and moderate values. Maternal genetic correlationsbetween them were positive and of low values. An antagonistic direct-maternal correlations from Model 3 withintraits and between traits indicated that offspring of does with superior maternal abilities probably may provide an inferiordirect genetic effect in the same trait and between traits. It was therefore possible to rapidly improve WW and KR in thisgoat population through selection, while the adverse effects of direct-maternal correlation within and between traits shouldbe considered. The best fit model would be a model including maternal genetic effect without a direct-maternal genetic covariance.

Keywords

• genetic parameters
• Thai goat
• Kleiber ratio
• weaning weight