Estimation of variance components for individual piglet weights at birth and at 14 days of age

Abstract

Individual piglet weights were recorded at birth (IPWB) and at 14 days (IPW14) in three maternal lines over a time period of two years. The data included 24329 IPWB and 13640 IPW14 records from 2297 litters, 1797 dams and 180 sires. The piglet data included two generations only which may have limited the reliable simultaneous estimation of direct and maternal heritabilities and the litter effect. Consequently, a number of different models were employed to estimate these effects. Heritabilities were 0.03 for IPWB and 0.04 for both, IPW14 and growth rate from birth to 14 days (ADG14). The maternal genetic effect was larger for IPWB (m²: 0.22) than for IPW14 (m²: 0.13) and ADG14 (m²: 0.09). In contrast, litter effect estimates were lower for IPWB (c²: 0.10) than for IPW14 (c²: 0.22) and ADG14 (c²: 0.22). Overall, these results agree well with estimates presented in previous studies. Individual piglet birth weight is labour intensive to record, has a low heritability and low genetic relationship with post-natal growth limiting its use for genetic improvement of piglet performance.