Genetic Analysis of Osteochondrosis and Leg Weakness in the Swedish Pig Progeny Testing Scheme

Abstract

Information about leg weakness scored before slaughter (1 =worst, 3=best) and osteochondrosis in elbow and knee joints scored after slaughter (0=best, 5=worst) in the Swedish pig progeny testing scheme were analysed. The data comprised information on 9 886 pigs (5 568 Landrace and 4318 Yorkshire) beginning test from November 1981 to September 1984. For the two osteochondrosis scores and leg weakness, Landrace was the inferior breed and castrates the inferior sex. The incidence and severity of osteochondrosis was highest in the knee joint, compared with the elbow joint. Only severe joint lesions were correlated with increased incidence of clinical signs of leg weakness. Pigs with inferior constitution grew faster during the first part of the test period, but slower at the end of test compared with constitutionally better pigs. Heritabilities of leg weakness score were 0.14±0.03 for Landrace and 0.11 ±0.03 for Yorkshire. Heritabilities for elbow joint scores for osteochondrosis were 0.21±0.03 and 0.25±0.04 for Landrace and Yorkshire respectively. Corresponding heritabilities for knee joint scores were 0.33±0.04 and 0.35±0.05. Indications of unfavourable genetic correlations between constitution and growth rate and between constitution and lean percentage were found.