Phenotypic and Genetic Associations among Carcass Traits of Swine2

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Abstract
The genetic variation and the phenotypic and genetic associations among carcass traits were examined, using data from five breeds of swine from the North Carolina Swine Evaluation Station and the North Carolina Agricultural Experiment Station. Seventeen traits, most of which were related to meat quality, were studied. Data were collected over a period of 2 years from 585 pigs representing 268 dams and 116 sires. Estimates of heritabilities and genetic correlations were obtained, using nested variance and covariance analyses. Significant breed differences were found for all the traits. The phenotypic correlations of backfat thickness, I. dorsi area and percent lean cuts with meat quality characteristics were generally low. Backfat thickness, area of I. dorsi, percent lean cuts, ether extract, total moisture, expressible juice and taste panel scores for fatness and flavor were highly heritable (h2≱0.40) and firmness, color, meat film area, shear value and softness scores were moderately heritable (0.20≱h2≱0.40). Low heritability estimates were obtained for pH, subjective weeping score, marbling and juiciness. Genetic correlations indicated that effective selection for lower backfat thickness, and/or increased area of l. dorsi and percent lean cuts would yield meat with a lower waterholding capacity, lower intramuscular fat content, higher shear value and lower scores for juiciness and flavor. Thus, it seems likely that it will become necessary to select directly for meat quality. Since expressible juice and ether extract are objective measures highly related to meat quality, these traits would be the logical selection criteria for meat quality. Moreover, improvements in these traits would be expected to improve the organoleptic properties of the muscles. Copyright © 1967. American Society of Animal Science . Copyright 1967 by American Society of Animal Science