Genetic Association between Age and Litter Traits at First Farrowing in a Commercial Pietrain-Large White Population in Thailand

Abstract

Genetic associations between age at first farrowing (AFF), number born alive (NBA), stillborn and mummy (LOST) and total birth weight of live piglets (TBW) were estimated using data from 1777 Pietrain (PT) and 450 Large White (LW) sows gathered from 1999 to 2006 in a commercial swine population. All pigs were halothane gene negative, reared in an open-house system and given the same diet, management and health care. The variance and covariance for AFF, NBA, LOST and TBW were estimated using average information restricted maximum likelihood procedures and subsequently used to calculate heritabilities and genetic correlations. A four-trait animal model (AFF-NBA-LOST-TBW) was used that accounted for contemporary group (year-month) and breed as fixed effects and animal and residual as random effects. Large White pigs had shorter AFF (10.00 ± 2.34 d; P < 0.01), more NBA (1.20 ± 0.22 piglets; P < 0.01), less LOST (0.20 ± 0.11 piglets; P < 0.01) and lighter TBW (1.11 ± 0.30 kg; P < 0.01) than PT pigs. Heritability estimates were 0.06 ± 0.03 for AFF, 0.11 ± 0.04 for NBA, 0.08 ± 0.04 for LOST and 0.08 ± 0.03 for TBW. Genetic correlations between AFF and NBA (0.19 ± 0.26), LOST (-0.11 ± 0.33) and TBW (0.14 ± 0.32) were low. These low correlation estimates indicated that selection for AFF could be carried out in this commercial swine population without severe undesirable effects on litter traits.