LAUSR

Abstract Tail-biting in pigs affects the health and welfare of the animals. Different indicators, such as the tail posture, can be used to detect tail-biting at an early stage. The aim of this study was to investigate the effect of tail-directed behaviour, differentiating between tail-biting and tail-in-mouth behaviour, on tail lesions and tail posture of 6 groups of 24 undocked piglets in identical pens using detailed behavioural observations of the four days (t-1 to t-4) before a tail-biting outbreak. Tail lesions were scored twice a week. The tail posture and the tail-directed behaviour were recorded using video observation. Generalised linear mixed models were used separately for tail-biting and tail-in-mouth behaviour to test the influence of the number of receiving (RT) or performing (PT) tail-directed behaviour on the multinomial tail lesions (0: no tail lesion, 1: superficial tail lesion, 2: small or large tail lesion) and to test the influence of RT and PT and the fixed effects of pen (1-6), day (t-1 to t-4), hour (10:00 h – 17:00 h), location (at the trough, not at the trough) and receiver (received tail-directed behaviour in the previous 20 min, received no tail-directed behaviour in the previous 20 min) on the binary tail posture (0: raised tail posture, 1: lowered tail posture). For the tail-biting behaviour dataset, the results showed that piglets with a higher RT had significantly more severe tail lesions (p