Submitted to: Animal Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 16, 2005
Publication Date: December 5, 2005
Citation: Rohrer, G.A., Thallman, R.M., Shackelford, S.D., Wheeler, T.L., Koohmaraie, M. 2005. A genome scan for loci affecting pork quality in a Duroc-Landrace F2 population. Animal Genetics. 37:17-27. Interpretive Summary: Palatability traits of pork products are important for the pig industry to maintain domestic consumer demand and to increase international demand. Therefore, a Duroc-Landrace cross population was developed to identify regions of the pig genome that influence pork palatability traits. Significant results indicate chromosome 1 has two important locations, one affecting marbling of the loin muscle and the other affecting darkness of the lean tissue. Chromosome 2 has a region affecting tenderness of cook loin chops, chromosome 17 has a region that affects size of the loin muscle and the X chromosome has a location affecting carcass weight in females. Over 50 other associations that may be important were also discovered. Results indicate that development of genetic markers to improve the palatability of pork through marker assisted selection is possible. These findings should be directly applicable to commercial production as the germplasm used is similar to US pig populations.
Technical Abstract: A genome scan was conducted on 370 F2 Duroc-Landrace pigs. Microsatellite markers (n = 182) were genotyped across the entire F2 population, all F1 parents and the paternal grandparents. Breed of origin of all chromosomal segments inherited in F2 progeny were predicted using GenoProb, where genotypic data, genetic maps and extended pedigrees were used as inputs. Statistical tests for QTL associations were conducted on 41 phenotypes with SAS using output from GenoProb for genotypic data. Fixed effects included sex and age at slaughter. For certain analyses carcass weight, RYR1 genotype and/or PRKAG3 genotypes were also included as covariates. Subjective and objective measures of pork quality were recorded as well as measures of carcass composition. Test results were adjusted to a genome-wide level of significance. Five genomic regions presented significant evidence for QTL (approximate locations were chromosome 1 positions 6 and 67 cM, chromosome 2 position 62 cM, chromosome 17 position 50 and X position 87 cM) for six traits. Sixty-six suggestive associations were detected. Fourteen of these associations were within the regions with significant QTL on chromosomes 2, 17 and X, and the remaining 52 associations resided in 29 other regions on 13 different chromosomes of the porcine genome. The chromosome 2 region of 60-66 cM affected all measures of pork tenderness and the region on chromosome 17 (32-39 cM) affected both measures of intramuscular fat and loineye area. Many of these QTL should be useful in commercial production to improve pork quality as the population was developed from two of the three most utilized breeds of swine in the U.S.