Genetic correlations between carcase length, fat and muscle depths and primal cut weights in the French Large White Sire line

Records for the French national Large White sire line were collected between 1999 and 2008 for 65,082 pigs on farm and for 2,429 carcases of siblings measured in three test stations. Ultrasonic measures of backfat and muscle depth were recorded in vivo on farm. In addition, fat and muscle depth as well as length were recorded on carcases of littermates. Weights of primal cuts included back leg, loin with the skin and fat trimmed as well as shoulder and belly weights. Heritability estimates were moderate to high for the four primal cuts, ranging from 0.21 for shoulder to 0.46 for back leg weight. Estimates of genetic correlations (ra) showed back leg weight was genetically independent from loin (ra: 0.06) and shoulder (ra: 0.01) weights. Belly weight was negatively correlated with the weight of the three other cuts (ra: -0.57 to -0.33). The heritability of carcase length was high (0.64) but the genetic correlations between this trait and weights of primal cuts were low (ra: 0.05 to 0.26) limiting its use as a potential selection criterion for these traits. Estimates of genetic correlations between fat and muscle depth with primal cut weights were generally higher for fat and muscle depth measured on the carcase in contrast to 'in vivo' measures.