Effect of sire on pig leg health in commercial organic herds

Wallenbeck, A. ¹, Eliasson, Christina.¹ and Alarik, Maria²

¹Swedish University of Agricultural Sciences, Department of Animal Breeding and Genetics,^, Box 7023, 75007 Uppsala, Sweden. ²Seniour pig production advisor, Swedish Rural Economy and Agricultural Societies (Hushållningssällskapet), Uppsala, Sweden

In Sweden, the proportion of pigs from organic herds with leg joint remarks at slaughter has increased from 4 to 8 % over the past decade, partly due to osteochondrosis and partly to infectious inflammation (Erysipelas). This study assessed differences in locomotion, lameness, swollen joints and joint remarks at slaughter between sire breeds (Hampshire (H) and Duroc (D)) and between individual sires. In total, 180 Yorkshire x Landrace sows from organically certified commercial herds were inseminated with non-mixed semen from AI boars. The two sire breeds were evenly distributed among sows in each herd and production batch. The study was carried out during 2012. Locomotion, lameness and swollen joints were individually assessed at approx. 30 and 100 kg live weight and slaughter remarks were recorded for each individual pig. Analysis of variance was performed with the procedures GLM and MIXED in the SAS package.

Preliminary results based on information from 698 pigs indicate that the prevalence of clinical lameness increased from 5 to 21 % and that of swollen joints from 0.8 to 8.6 % over the growing/finishing period. However, the proportion of pigs with joint remarks at slaughter was only 2.4% and was not significantly correlated to any of the live leg health assessments. As expected, the recording of lameness was correlated to the recording of locomotion on both assessment occasions (r=0.47, p<0.001 at 30 kg; r=0.44, p<0.001 at 100 kg). There were no differences between sire breeds (H and D) for any of the leg health parameters investigated (p>0.05), but there were substantial variations in locomotion scores associated with individual sires, both at the first (p=0.036) and second (p=0.087) assessment. More detailed investigations of this limited dataset showed that among H-offspring the effect of the individual sire accounted for 12 and 15 % of this variation at first and second assessment respectively, indicating moderate to high heritability. However, among D-offspring the corresponding variations were 0.2 and 0 %. In conclusion, joint remarks reported at slaughter have no, or very weak, associations to clinical lameness and swollen joints. This study does not provide evidence that leg health can be improved by choice of sire breed, but the variation observed between individual sires indicates that leg health may be improved by choosing the best sires.