Kim, J., Lee, J., Kang, K. et al. 2023. Effects of sling belt provision on behaviour, skin lesions, and salivary cortisol level in growing pigs after transport and regrouping. Applied Animal Behaviour Science 269, 106116.

The provision of enrichment material has been widely recommended to mitigate stress and minimise aggressive behaviour as well as enhance the welfare of pigs after transport and regrouping. In this study, we assessed the effects of providing a polyester sling belt (SB) on behaviour, number of skin lesions, and salivary cortisol levels in growing pigs shortly after transport and regrouping. A total of 571 pigs (29.6 ± 2.4 kg) were allocated to one of the following three treatment groups: 1) C: control group, 2) SB5: provision of 5–6 SB per pen, and 3) SB10: provision of 10–12 SB per pen. After being transported for 2 h, the pigs were housed in pens having fully slatted floors and regrouped with unfamiliar pigs. Their behaviours after regrouping were observed via 24-h video recording. Body weight and number of skin lesions were assessed on days 0 (the day of transport and regrouping) and day 6. Saliva samples were collected from nine pigs per treatment on days 1 and 2. The SB10 group exhibited significantly lower levels of injurious interaction than did the C group (P < 0.05). This injurious interaction tended to have positive correlations with the salivary cortisol levels on day 2 (r = 0.64, P = 0.06) and the changes in the proportion of pigs with skin lesion score (1+2) from day 0–6 (r = 0.66, P = 0.05). Furthermore, it was positively correlated with the proportion of pigs with skin lesion score (1+2) on day 6 (r = 0.80, P = 0.01). Additionally, manipulation behaviour towards the SB showed a negative correlation with skin lesions on day 6 (r = −0.70, P < 0.05) and also displayed a negative tendency to be correlated with salivary cortisol levels on day 2 (r = −0.64, P = 0.06). During the study period, the SB10 group exhibited the greatest reduction in the proportion of pigs with skin lesions than did the other groups (P < 0.05). Salivary cortisol levels did not differ significantly among the treatment groups on day 1; nevertheless, the lowest level was observed in the SB10 group on day 2 (P < 0.05). In conclusion, providing SB to growing pigs housed in pens with slatted flooring shortly after transportation and regrouping can improve their health and welfare by reducing injurious behaviour, skin lesions and activity in the HPA-axis suggesting stress.