Characterization of swine adiponectin and adiponectin receptor polymorphisms and their association with reproductive traits.

In this study, polymorphisms in genes encoding porcine adiponectin (ADIPOQ) and its receptors (ADIPOR1 and ADIPOR2) were evaluated for associations with reproductive traits in a Landrace sow population. Sixteen SNPs were identified, and among these, associations were found between reproductive traits and five SNPs. Heterozygous multiparous females for SNP ADIPOQEF601160:c.178G>A had fewer stillborn piglets (P < 0.05) and shorter weaning-to-oestrus intervals (P < 0.05). Multiparous females bearing the mutant allele for SNP ADIPOQEF601160:c.*1094_1095insC gave birth to fewer stillborn piglets (P < 0.05). In addition, selection for the ADIPOQ [A;C] haplotype is expected to result in multiparous sows having the lowest number of stillborn piglets and shorter weaning-to-oestrus intervals. In second-parity sows, the polymorphism in ADIPOR1 (AY856513:c.*129A>C) showed significant associations with live-born (P < 0.01) and stillborn (P < 0.05) piglets. In multiparous sows, a significant association was observed for an ADIPOR2 polymorphism (AY856514:c.*112G>A), with the c.*112GA genotype associated with shorter weaning-to-oestrus intervals (P < 0.01). Haplotype analyses of ADIPOR2 SNPs revealed that selection in favour of the [A;C] haplotype and against the [G;G] haplotype may result in sows having an increased number of live-born piglets and shorter weaning-to-oestrus intervals. We have therefore described specific SNPs and haplotypes that are associated with large litter size, fewer stillborn and mummified piglets and shorter weaning-to-oestrus intervals. Selection for these SNPs and haplotypes is a strategy to improve reproductive success in pigs.