Can tail-in-mouth behaviour in weaned piglets be predicted by behaviour and performance?

Abstract

This study aimed to identify characteristics of pigs performing tail-in-mouth behaviour (TIM; P, n=34), their recipients (R, n=23) and neutral penmates (N, n=31) at two occasions, the first being at weaning (4 weeks of age) before TIM was observed in the pen and the second being at 9 weeks of age when TIM had emerged, but no clinical tail lesions were observed. The groups (n=22) were formed by siblings, two gilts and two castrates. Behaviour was analysed as 24-h time budgets and continuously sampled during 30min of the active part of the day. Category (P, R, N) effects were analysed at individual and (directed) dyad level.P was born significantly smaller than R, but the difference had disappeared at 4 weeks. Growth or sex distribution did not differ between categories. Category differences in performed behaviour were evident at 4 weeks of age, when P showed more overall activity and environmental exploration as compared to R, as well as more bouts of tail-nosing than N. Different aspects of behaviour changed in the different categories between 4 and 9 weeks of age. In P social activity increased significantly and went from no preference at 4 weeks to a significant preference for social actions for R over N at 9 weeks. N was socially passive at 9 weeks while receiving more social behaviour than the other categories. These differences in behaviour suggest that the categories represented different phenotypes of pigs.