Estimation of variance and genetic parameters for pre-weaning weights of individual Landrace X Desi synthetic piglets

Abstract

Variances and genetic parameters were estimated for birth weight (BW), 14 day body weight (14dW), 28 day body weight (28dW), 42 day body weight (42dW) and weaning weight or 56 day body weight (56dW) in the Landrace X Desi synthetic piglet population reared under sub-temperate agro climatic region of India. The data were analyzed using restricted maximum likelihood (REML) fitting six animal models with various combinations of direct and maternal effects. Estimates of genetic and permanent environmental correlations were obtained using bivariate analysis of an animal model and computed with the DFREML program. A log likelihood ratio test was used to select the most appropriate univariate model for each trait. The direct estimates of heritability were 0.43 ± 0.04, 0.31 ± 0.04, 0.35 ± 0.05, 0.40 ± 0.06, and 0.49 ± 0.06 for BW, 14dW , 28dW , 42dW, and 56dW, respectively and it increased with age from 14dW to 56dW. The permanent litter effect progressively decreased and was minimum at 56dW, ranged from 0.21 ± 0.06 to 0.34 ± 0.04. Further, maternal genetic heritability was the highest, ranging from 0.16 ± 0.07 (model 5) to 0.18 (model 6), at age of weaning and the lowest for BW, from 0.04 ± 0.03 (model 5) to 0.06 (model 6). The presence of permanent litter effect was more important since it increased the accuracy of last three models (models 4–6) significantly over the first three models (models 1–3) without permanent litter effect. The selection of 56dW would be more reliable for genetic progress rather than the selection of BW. The direct additive genetic correlation (r a) between BW and 56dW was−0.158 ± 0.29 which revealed that higher BW may not result for favorable changes in weaning weights which was in contradiction to many earlier reports.