Genetic parameters for bone strength, osteochondrosis and meat percentage in Finnish Landrace and Yorkshire pigs.

Osteochondrosis (OC) is a major factor causing joint problems that affect animal welfare and pork production profitability. Strong bones are also important in the slaughtering process, especially as broken bones can lead to rejections of parts of the carcass. In this study, 326 Finnish Yorkshire and 464 Finnish Landrace test station pigs were examined post mortem for bone strength and osteochondral lesions. The objective was to estimate genetic parameters for OC and bone strength and their genetic and phenotypic correlations with carcass meat percentage. Two formulas were used for lean meat percentage, the first one (Hennessy meat-%) comprising two fat thickness measurements and one muscle depth measurement, and the second one (test station meat-%) also including the weight of lean meat in ham. Finnish Yorkshire had stronger bones than Finnish Landrace on average, but also more OC in the proximal end of the humerus (36%) and the distal end of the femur (51%) than Finnish Landrace (29% and 31% OC in the humerus and femur, respectively). By using the data on both breeds, the OC heritability estimated was 0.05 in the humerus and 0.26 in the femur. The estimated heritability of bone strength was also moderate (0.26). Test station meat-% showed higher heritability (0.40) than meat-% based on the Hennessy formula (0.29). Genetic correlations between meat percentage and the other studied traits were weak and associated with high standard errors. The results show that a mild form of OC is common in both Finnish pig breeds; bone strength and OC in the distal end of the femur are moderately heritable and can be improved through selection; and selection for high meat percentage does not seem to affect bone strength or OC.