Genetic risk factors for tail biting in Australian pigs as determined by binomial regression models

Tail biting has adverse welfare implications and is a costly challenge in commercial pig farms. Tail biting incidents can be reduced by breeding animals with reduced susceptibility to becoming a victim of tail biting. This paper aims to quantify genetic risk factors for being a victim of tail biting. Data on 55,373 pigs representing 9 genetic lines were collected. Pigs were housed on 8 commercial farms in Australia under a range of housing and climatic conditions. Genetic risk factors were compared between lines, breeds and sire or dam types. Line, breed, and line type were all significant risk factors for tail biting (P < 0.0001). Landrace pigs and sire lines were least affected by tail biting. Female pigs were generally bitten more often (P = 0.005) than males, and while there were significant sex-line interactions, these were not observed for breed or line type. Pigs were more likely to receive tail biting if they experienced more days outside thermoneutral temperatures, defined as 15 to 30℃. Some lines were more affected by temperature stress than others. The Large White breed and dam lines showed the least tail biting during temperature stress. To minimise tail biting, pig farmers are encouraged to consider estimating tail biting risk per line, identify sex differences, and/or reducing temperature stress.