Identification of candidate genes for fat deposition in heavy pigs

Fatness is a very important trait to produce tights and meat suitable for seasoned products, like San-Daniele ham, and represents one the main targets of the Italian pig breeding industry. Association studies between genotypes and fat deposition can help breeders to select boars and sows with favorable characteristics. In the present study, 103 SNPs distributed on 52 candidate genes were analyzed in a population of 800 pigs, crosses of Italian Duroc X Large White (400 pigs) and Commercial hybrid X Large White (400 pigs). Pigs were reared in commercial farms, with similar feeding and environmental conditions. At slaughterhouse, carcass weight, tight weight, lean percentage calculated with FOM, mm of lean and mm of backfat were recorded and a muscle sample was collected for chemical composition and for DNA analyses for each animal. SNPs were chosen in promoter regions of genes already known for association with fat traits according to available researches. Regulatory regions represent a very interesting target for research due to their effect on gene expressions and, potentially, on phenotypes. On the basis of allele frequencies, 67 SNPs were segregating in both hybrids, while 6 SNPs segregated only in Duroc x Large White (ACACA, CTSK, FABP3, OPN, PLIN2, SCD). Association analysis with intramuscular fat (%) and backfat thickness (mm) was carried out with Pearson correlation test and Bonferroni correction and evidenced significant correlations (P<0.01) between fat traits and analyzed polymorphisms. Genes with significant SNPs for investigated traits were ACACA, ATP1A2, CAPNS1, CCKAR, CTSK, CTSL, GH, ID3, MYOD, OPN, PLIN2, PPARGC1A. Correlations with grow traits as carcass and ham weight were also found.