Heritability of clinical tail-biting and its relation to performance traits

Clinical tail-biters were identified over a 12-month period at a commercial nucleus pig-breeding farm that had a history of tail-biting problems. The breed, gender, and relative size of the tail-biters were recorded. Using pedigree data for all the pigs on the farm at the time of observations, the heritability of the tail-biting behaviour was estimated for purebred Large White (LW) and Landrace (LR) pigs. The incidence of tail-biting was 2.8% for Large White and 3.5% for Landrace (breed effects, P<0.10). Tail-biting was found to be heritable in Landrace (h2=0.05±0.02, P<0.05 as a 0-1 trait, equivalent to h2=0.27 as a continuous trait), but not heritable in Large White pigs (h2=0.00±0.00, as a 0-1 trait). In the Landrace population, tail-biting was unfavourably genetically correlated with leanness [lean tissue growth rate (LTGR; rg=0.27, P<0.05), and back fat (BF) thickness at 90 kg (rg=−0.28, P<0.05)]. It is concluded that past selection for desirable production traits may have resulted in increased predisposition to exhibit tail-biting behaviour. From the correlations and covariance matrix reported, it would be possible to develop a selection index to reduce the predisposition to exhibit tail-biting behaviour through selective breeding.