Estimation of variances from additive and dominance effects for litter sizes traits in Large White and Landrace sows

Abstract

Genetic analysis of additive and dominance gene effects on litter traits, namely, born alive (BA), birth weight (BW), number weaned (NW) and weaning weight (WW) of purebred Large White and Landrace sowsfrom a commercial farm during 1992-2002 were conducted. Data were analyzed using two mixed model equations. The first model included fixed effects and random effects identifying inbreeding depression, additivegene effect and permanent environments. The second model was similar to the first model plus dominance gene effect. Heritability estimates of BA, BW, NW and WW from two models were 0.145-0.178, 0.162-0.220,0.037-0.087 and 0.152-0.237 of large white and landrace respectively. Proportions of dominance effect to total phenotypic variance from the dominance model were 0.014, 0.163, 0.047 and 0.154 for large white and 0.026,0.020, 0.020 and 0.0003 for landrace, for BA, BW, NW and WW. Dominance effects were found to have small sizable influence on the litter sizes traits analyzed. Therefore, genetic evaluation with animal model (model 1)is found more appropriate and less time consuming when compared with dominance model (model 2).

Keywords

• inbreeding depression
• additive
• dominance
• litter traits
• pig.