Association analyses of candidate SNP on meat quality traits in swine

An important aim of Italian pig selection is to obtain animals having high aptitude for PDO dry-cured ham production. The efforts of the last years are directed to SNP identification for future large scale association studies. Here five SNP in three candidate genes for meat quality (CRADD, PTPRD, PIK3R2) were found analyzing twenty-two animals representing the extreme tails of the distribution for three phenotypes (muscle compactness, fat thickness and the principal component 1) of 231 Large White x Landrace individuals. The principal component 1 was calculated considering nine phenotypes (muscle compactness, marbling, colour uniformity, fat covering, colour, dorsal fat thickness, ham fat thickness, vein system and final score) and was correlated (P<0.0001) with seven of them with absolute correlation values ranging from 0.37 to 0.91. GLM procedure was used for association analysis with meat quality traits. A CRADD [A/G] SNP showed a significant association with muscle compactness (P=0.0498), whereas a PTPRD [G/T] SNP and a PIK3R2 [C/T] SNP with muscle compactness (P=0.0195 and P=0.0014, respectively) and backfat thickness (P=0.0265 and P=0.0087, respectively). The SNP were also tested in more than 500 animals belonging to three Italian breeds (Large White, Duroc, Landrace), with extreme EBVs for fat or growth traits. The PIK3R2 [C/T] SNP showed significant associations (P<0.01) with backfat thickness, average daily gain, feed conversion rate and lean cut yield in Landrace, whereas the PTPRD [A/G] SNP showed a significant association with thigh weight (P=0.0251) in Large White.