Identification and Evaluation of Quantitative Trait Loci Influencing Carcass Composition and Meat Quality Traits in Pigs

The MSU F₂ Duroc x Pietrain resource population was used to identify quantitative trait loci (QTL) for carcass and meat quality traits by applying three least-squares models; line-cross (LC), half-sib (HS), and combined line-cross and half-sib (CB). A subsequent validation study was conducted for selected QTL regions in a US commercial Duroc population. Following an initial genome scan using 510 F₂ pigs with 124 microsatellite markers, 20 additional markers on 9 chromosomes were genotyped for 954 F₂ pigs and 20 markers used in the first scan were genotyped for 444 additional F₂ pigs. A total of 91 QTL segregating between and within parental breeds were identified for carcass and meat quality traits (FDR ≤ 0.05). Based on these results, five putative QTL regions (SSC3, 6, 12, 15 and 18) for carcass and meat quality traits were selected for further evaluation in a purebred Duroc population. A total of 81 gene-specific single-nucleotide polymorphisms (SNP) were genotyped of which 33 were segregating and were analyzed for associations with pH, color and marbling, and age, backfat thickness and LMA adjusted to 113 kg. Significant associations were observed with pH, marbling score and L* (P ≤ 0.05), which were consistent with the genome scans. Identification and subsequent validation of QTL influencing carcass composition and meat quality traits in resource and commercial populations will facilitate successful implementation of marker assisted selection programs in order to achieve genetic improvement.