GENETIC EVALUATION OF GROWTH PERFORMANCE OF LARGE WHITE PIGS REARED UNDER INTENSIVE MANAGEMENT SYSTEM IN KENYA

Abstract

Pig production in Kenya is characterized by lack of genetic performance parameters, crucial in setting up sustainable genetic improvement strategies. To partly address this situation, random regression (RR) models have been applied in a varied range of longitudinal data from pigs to other animals. The objective of this study was to undertake genetic evaluation of growth performance of large white pigs reared under intensive management systems in Kenya. Growth data was obtained from KALRO-Naivasha and consisted of body weight (BW) records from 1,398 pigs. The fixed effects of the model used, included dam parity, piglet sex and contemporary groups while litter size at birth was treated as a linear covariate. Random regressions for weight on Legendre polynomials (LP) were included for direct additive gene, maternal additive genetic and permanent environment. Residual effects were modeled to account for heterogeneity of variance by age. Estimates of phenotypic variance increased with age from 3.43 ± 0.28 (3rd week) to 2,449.28 ± 392.07 (36th week), while estimates of direct additive genetic heritability (h2) ranged between 0.20 ± 0.04 and 0 .52 ± 0.08. Similarly, maternal additive genetic heritability (m2) increased from 0.26 ± 0.05 to 0.79 ± 0.04 while the ratio of permanent environmental variance to phenotypic variance (e2) ranged between 0 ± 0.01 and 0.15 ± 0.10. Direct additive genetic correlations were greater than 0.48 between all measures of weight and decreased with increase in age interval. The first three eigenvalues of the coefficient matrix of the additive genetic covariance accounted for 98.62 % of the sum of all the eigenvalues. Growth was highly heritable at pre-weaning age and influenced by maternal and common environmental effect. This study found the highest heritability at the 8th week of growth and recommends selection for increased growth at the same age.