Tail docking and the rearing of heavy pigs: the role played by gender and the presence of straw in the control of tail biting. Blood parameters, behaviour and skin lesions.

This study evaluated whether the specific heavy pig rearing context allowed the fattening of undocked pigs without an outbreak of tail biting. At the same time, gender and straw availability (small amounts) were considered to understand their possible interactions with tail presence in the display of tail biting. A 2 × 2 × 2 factorial design was adopted to test the effects of these factors on blood parameters, behaviour and tail/ear lesions. Few interactions among factors were detected. Undocked pigs showed lower cortisol (P<0.02), lying behaviour (P<0.001), and higher risk of tail/ear biting (weeks 3 and 9), but lower risk of tail lesions (week 14). Straw increased the motivation for exploring (P<0.001), reduced serum haptoglobin (P<0.001) and the risk for tail biting (weeks 3, 9, 18) and ear biting (weeks 3, 9). Results highlight the importance of straw as an environmental enrichment and seem to indicate that fattening undocked heavy pigs is possible.