Effect of porcine IL-6 polymorphism on litter size traits in commercial pig breeds

This study aimed to verify the polymorphisms in the porcine IL-6 gene and to elucidate its effects on litter size traits in Large White and Landrace sows. Four single nucleotide polymorphisms (SNPs) of the porcine IL-6 gene (g.91506415A>G, g.91507983A>G, g.91508173C>T, and g.91508716C>T) were genotyped using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. There was no polymorphism observed on the three SNPs (g.91506415A>G, g.91507983A>G, and g.91508716C>T) of the porcine IL-6 gene. The porcine IL-6 g.91508173C>T polymorphism was found to be segregating in Large White and Landrace sows. The porcine IL-6 g.91508173C>T polymorphism was significantly associated with the total number born (TNB) and the number of piglets weaned alive (NWA) traits in Large White sows (P<0.05). Moreover, the porcine IL-6 g.91508173C>T polymorphism was significantly associated with the TNB, number born alive (NBA), and NWA traits in Landrace sows (P<0.05). These results indicated that the porcine IL-6 g.91508173C>T polymorphism was associated with litter size traits. These findings confirmed the importance of the IL-6 gene as a candidate gene for litter size traits in pigs.