Genetic effects of IGF-1 gene on the performance in Landrace x Lantang pig resource population.

A Landrace x Lantang resource population (LL-SCAU) including 216 F2 pigs was founded by F2 design for analysis of IGF-1 gene polymorphism by PCR-RFLP. The least square means of divergent IGF-1 genotypes for the measured traits were estimated with the fixed model. The genetic effects of IGF-1 gene were estimated with a mixed model and the additive and dominant effects of IGF-1 gene were accordingly calculated. The results of the fixed model and the mixed model showed that IGF-1 locus significantly affected average daily gain after weaning. Average daily gain after weaning for AA genotype on IGF-1 locus was 20.58 g (P = 0.0347) higher than for AB. The additive and dominant effects attributed to IGF-1 were 1.78 g and -18.81 g respectively. IGF-1 locus also significantly affected carcass composition. Bone percentages for AA and AB on IGF-1 locus were lower than for BB by 5.22% (P = 0.0008) and 5.19% (P = 0.0007) respectively, and the additive and dominant effects were -2.61% and -2.58% respectively. Amount of carcass lean for AA on IGF-1 locus was less than for AB by 0.45 kg (P = 0.0264), and the additive and dominant effects were 0.16 kg and 0.61 kg respectively. Skin and fat percentage for AA and AB on IGF-1 locus was higher than for BB by 8.81% (P = 0.0206) and 7.64% (P = 0.0431) respectively, and the additive and dominant effects were 4.41% and 3.24% respectively. The genetic analysis of IGF-1 gene showed that IGF-1 locus significantly affected average daily gain after weaning, bone percentage, carcass lean, skin and fat percentage. The estimated additive and dominant effects showed that only the additive effect of IGF-1 locus on skin and fat percentage was much higher than dominant effect, and IGF-1 gene can be used as a major gene for effective selection of these traits.