Random regression analyses using B-spline functions to model the growth of large white pigs

The pigs industry in Kenya has faced many challenges, among them poor animal genetic resource base. To partly address this, genetic parameters were estimated using B-spline functions in random regression models for weight of Large White pigs measured between the 3rd and 36th week of age. The model accounted for contemporary groups, parity and sex as fixed effects while random effects modeled were; animal genetic effect, permanent environmental effect and maternal genetic effect along with heterogeneous residual variances. Heritability estimates decreased with age from 0.37 at 3 weeks to 0.27 at 36 weeks. Weight during the studied period showed initial positive genetic (0.20 – 0.91) and phenotypic correlations (0.25 – 0.91), which decreased with increase in age gap. The results from this study shows that body weight in Large White pigs is moderately heritable (0.27-0.37), especially prior to weaning, suggesting the potential for genetic gain from selection. The genetic correlations suggests that considerable genetic gain can be obtained by considering pre-weaning weight only, though the genetic correlation less than unity indicates that more genetic gain would be realized by including all the estimates of heritability throughout the growth period. In all cases, the estimates generated by this study were consistent with previous studies . This study suggests that random regression methods using B-spline are appropriate for estimating genetic parameters and genetic gain for weight in Large White pigs.