An observational study on tail biting in commercial grower-finisher barns

Objectives: To describe the prevalence of bitten tails and determine risk factors at pig and pen level in barns with a history of high incidence of tail biting. Methods: In two finishing barns, prevalence and severity of tail-biting lesions in docked pigs and association of bitten tails with gender were determined in a cross-sectional study. The associations with space allowance per pig, animal density, and barrow:gilt ratio per pen were examined. A matched case-control study determined the association between length of tail, severity of lesions on bitten tails, and chest girth (a surrogate measure of body weight). Results: In a total of 1895 pigs (58% barrows, 42% gilts), the prevalence of bitten tails was 16.3% (barrows 21%; gilts 9.4%). The odds of being a bitten barrow was 2.6 times higher than being a bitten gilt (P < .001). Approximately 60% of affected pigs of both genders had severe lesions. Neither prevalence nor severity of lesions was associated with space allowance, animal density, or barrow:gilt ratio within pen. The prevalence of bitten barrows was positively correlated with the percentage of gilts in the pen (r = 0.56, P = .001). Severely bitten pigs had significantly smaller chest girth than less affected pigs. No association of the severity of lesions with length of the tail was observed. Implications: Under the conditions of this study, the incidence of tail-biting lesions in barrows was more than twice that in gilts. Severely bitten pigs were smaller than pen mates. Sorting by gender may help reduce tail biting.