Heritabilities of osteochondral lesions and genetic correlations with production and exterior traits in station-tested pigs

Abstract

Osteochondrosis might reduce the performance of slaughter pigs, longevity of sows and animal welfare. The aim of the present work was to describe the prevalence in Swiss breeds and to analyse the genetic background of osteochondral lesions. Between January 2002 and December 2005, about 9500 station-tested pigs were examined for several exterior traits before slaughtering at the Swiss pig performance testing station using the Swiss linear description system with a scale from 1 to 7 per trait. The animals belonged to three breeds: Large White dam line, Swiss Landrace and Large White sire line. Additionally, a random sample of these pigs (n 5 2622) was examined for osteochondral lesions at seven positions of the carcass after dissection. At first, the surface and shape of the femur, humerus, radius and ulna at the joints were evaluated by a trained person. Afterwards these bones were sawed and the state of the cartilage and the distal epiphyseal cartilage of the ulna was examined at the cutting surface. Osteochondral lesions were scored on a scale from 1 to 6. The prevalence of osteochondral lesions was low at head of humerus, condylus lateralis humeri, radius and ulna proximal and head of femur. Osteochondral lesions at condylus medialis humeri (CMH), distal epiphyseal cartilage of ulna (DEU) and condylus lateralis femoris (CMF) exhibited phenotypic and genetic variance. Their heritabilities ranged from 0.16 to 0.18 using linear mixed animal models. Therefore, it is possible to reduce the prevalence of osteochondral lesions by selection in principle. Exterior traits showed low heritabilities (0.10 to 0.26) but several favourable genetic correlations with osteochondral lesions at CMH, DEU and CMF with low to moderate magnitude. Genetic correlations between osteochondral lesions and production traits were low.

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

“…Genetic correlation between OC scores in the front and rear legs was positive but only moderate (r g 5 0.31). Jorgensen and Andersen (2000) found stronger genetic correlation (r g 5 0.52) but Luther et al (2007) weaker genetic correlation (r g 5 20.14) between front and rear leg OC than in our study. A negative genetic correlation was observed between meat-% and OC in the humerus, indicating that pigs with high meat-% are genetically also more resistant to OC.…”

“…The heritability estimates for OC in the femur obtained in this study (h 2 5 0.26, both breeds combined) were higher than in the previously mentioned Swedish (h 2 5 0.21) (Yazdi et al, 2000) and in Swiss (h 2 5 0.18) (Luther et al, 2007) studies, but lower than in the Danish study (h 2 5 0.31 to 0.32) (Jorgensen and Andersen, 2000). The OC heritability in the humerus (h 2 5 0.09 to 0.25) was lower than OC heritability in the femur (h 2 5 0.31 to 0.32) both in our study and in the Danish study (Jorgensen and Andersen, 2000).…”

“…OC percentages in the femoral condyles were even higher: 97% and 73% for Swedish Landrace and Swedish Yorkshire castrated boars, respectively. In Swiss data (Luther et al, 2007), only 1% of test station pigs had osteochondral lesions in the proximal end of the humerus and 21% to 42% in the distal end of the femur (depending on the breed). Such large differences in OC prevalence between different countries and breeds may be explained by differences in genetic, housing and other population-related factors.…”

“…OC is more frequently found in the rear leg than in the front leg joints, and as many as half of the pigs can have some, usually mild, osteochondral lesions (Jorgensen and Andersen, 2000;Yazdi et al, 2000;Kadarmideen et al, 2004;Luther et al, 2007). The OC pathogenesis is characterized by a failure in matrix calcification or vascular -E-mail: pekka.uimari@mtt.fi invasion of an area of the growth cartilage and a subsequent failure in the conversion of cartilage to bone (Ekman and Carlson, 1998;Ytrehus et al, 2007).…”

“…The heritability estimates for OC in pigs are moderate, varying from 0.2 to 0.4 (Lundeheim, 1987;Jorgensen and Andersen, 2000;Yazdi et al, 2000;Kadarmideen et al, 2004;Jorgensen and Nielsen, 2005;Luther et al, 2007). The heritability of bone strength, however, has not been widely studied.…”