Study of porcine adiponectin (ADIPOQ) gene and association of a missense mutation with EBVs for production and carcass traits in Italian Duroc heavy pigs

The adiponectin (adiponectin, C1Q and collagen domain containing) encoded by ADIPOQ is an adipokine that modulates several biological processes such as lipogenesis, gluconeogenesis, fatty acid oxidation, glucose uptake and insulin sensitivity. An objective of this study was to identify SNPs in the ADIPOQ gene both in cosmopolitan and local pig breeds reared in Italy and in Meishan samples. Resequencing of ADIPOQ gene regions in 16 pigs of 12 breeds revealed only two SNPs (EU489740:g.1611G > A synonymous and EU489740:g.1735G > A missense mutations) already reported. The g.1735G > A polymorphism was genotyped by PCR-RFLP in 510 pigs from 11 breeds reared in Italy (Italian Large White, Italian Duroc, Italian Landrace, Belgian Landrace, Hampshire, Pietrain, Calabrese, Casertana, Cinta Senese, Mora Romagnola and Nero Siciliano) and from Chinese Meishan breed. The Italian local breeds were homozygous for the g.1735G allele while the Meishan samples resulted homozygous for the g.1735A allele. The polymorphism segregates in the cosmopolitan breeds, except for Hampshire, and the rarer g.1735A allele showed the highest frequency in Italian Duroc (0.12). Association analysis of g.1735G > A polymorphism with estimated breeding values (EBVs) for average daily gain (ADG), feed:gain ratio (FGR), weight of neck and loin (lean cuts, LC), weight of ham (H) and backfat thickness (BFT) were performed in Italian Duroc heavy pigs. The GA vs GG pigs showed higher least square means for ADG (P = 0.003) and LC (P = 0.036) EBVs and lower value for FGR EBV (P = 0.033).