Direct and maternal influences on the early growth, fattening performance, and carcass traits of pigs

This study investigates how direct (h) genetic effects, maternal (M) genetic effects, and litter environmental (c) effects influence the early growth, fattening performance, and carcass traits of pigs. This study provides new genetic knowledge about the relationship between early and later growth. Individual piglet weight records at birth, at 3 weeks, at weaning, and at 9 weeks were available for about 20,000 Yorkshire piglets. Performance records; average daily gain between birth and 90 kg live weight (DG(0-90)), between 25 and 90 kg live weight (DG(25-90)), and ultrasonic backfat thickness (at 90 kg live weight) were available for about 4000 pigs. The carcass records available for about 3000 pigs were linear backfat thickness, carcass length, and percentage of meat and bone in ham. Univariate and bivariate analyses were used to estimate (co)variance components. Piglet weight before weaning was influenced more by c(2) and m(2) than by h(2). The m(2) for individual piglet weight decreases with age from 0.18 to 0.09 between birth and 9 weeks, and h(2) increases from 0.07 to 0.12: No significant m(2) were present for DG(0-90) and DG(25-90). Estimation of m(2) and the correlation between direct and maternal genetic effects depend on data structure and pedigree relation ships. Low direct genetic correlations between piglet weight and growth during the fattening period were found (-0.00 to 0.37), which indicates together with the different origin (direct or maternal) of the genetic control for these traits the possibility to treat them separately in a breeding evaluation program. (C) 2003 Elsevier B.V. All rights reserved.