Abstract
BackgroundLeg weakness issues are a great concern for the pig breeding industry, especially with regard to animal welfare. Traits associated with leg weakness are partly influenced by the genetic background of the animals but the genetic basis of these traits is not yet fully understood. The aim of this study was to identify quantitative trait loci (QTL) affecting leg weakness in pigs.MethodsThree hundred and ten F2 pigs from a Duroc × Pietrain resource population were genotyped using 82 genetic markers. Front and rear legs and feet scores were based on the standard scoring system. Osteochondrosis lesions were examined histologically at the head and the condylus medialis of the left femur and humerus. Bone mineral density, bone mineral content and bone mineral area were measured in the whole ulna and radius bones using dual energy X-ray absorptiometry. A line-cross model was applied to determine QTL regions associated with leg weakness using the QTL Express software.ResultsEleven QTL affecting leg weakness were identified on eight autosomes. All QTL reached the 5% chromosome-wide significance level. Three QTL were associated with osteochondrosis on the humerus end, two with the fore feet score and two with the rear leg score. QTL on SSC2 and SSC3 influencing bone mineral content and bone mineral density, respectively, reached the 5% genome-wide significance level.ConclusionsOur results confirm previous studies and provide information on new QTL associated with leg weakness in pigs. These results contribute towards a better understanding of the genetic background of leg weakness in pigs.
Highlights
Leg weakness issues are a great concern for the pig breeding industry, especially with regard to animal welfare
Phenotypic correlations among fore leg score (FLS), rear leg score (RLS), fore feet scores (FFS) and rear feet scores (RFS) were low to medium, ranging from 0.19 to 0.44 (Table 1)
Our results reveal novel quantitative trait loci (QTL) regions on SSC2 for BMC, on SSC3 for head of the humerus (HH), on SSC6 and SSC18 for RLS, and on SSC14 for condylus medialis humeri (CMH), and support some previously reported QTL regions
Summary
Leg weakness issues are a great concern for the pig breeding industry, especially with regard to animal welfare. Leg weakness (LW) has a great impact on fitness and longevity of animals, which influences animal welfare and production and reproduction performance. Genetic correlations between LW-related traits and longevity in breeding sows have been reported and suggest that a better leg status would decrease involuntary culling [2,3]. Heritability estimates have been reported for LW in Duroc, Landrace, and Yorkshire sires i.e. 0.23, 0.30 and 0.39, respectively [4], and for an overall leg score in Landrace and Large White sows, i.e. 0.27 and 0.38, respectively [2]. OC is reported to have negative effects on important performance traits such as sow longevity, growth and feed conversion rate [12,13]
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