Behaviour and physiology of pigs under different levels of social contact
Description
Physical contact is a crucial aspect of social animals' life. Many studies corroborate the importance of social contact in pigs, but the direct impact of physical touch on their physiological and behavioural responses is largely unclear. The aim of this study was to investigate the influence of restrictions in physical contact in pigs. Subadult male and female pigs (n=77) were for one month housed either without the opportunity to engage in physical contact (‘alone’); in groups of three (‘group’), or with three hours of physical contact per day (‘intermediate’). Behaviour was observed by scan sampling observations (160 scans per pig). Body weight, salivary oxytocin and salivary cortisol were assessed pre- and post treatment. The results showed differences in behaviours expected to change due to the treatment, such as more lying in contact and less lying alone in the group housed pigs. The group housed pigs also showed less enrichment manipulation, but did not differ in the frequency of social contact as compared to the treatments with social restriction. Facing the neighbouring pen, recorded as reflection of contact seeking, did not significantly differ between the treatment groups. Sex differences for behaviour indicates that males (not castrated) were more active than females, and they were lying less in contact. Interactions between sex and treatment showed that males, specifically, in the intermediate treatment had a heightened interaction frequency in the 3 h period of social contact, and were lying less in contact. No treatment or sex effect, or their interaction, was seen on cortisol or oxytocin. Taken together, the results suggest that deprivation of physical contact influences behaviour, but not physiology in a sex-dependent manner for sub-adult pigs.
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Institutions
- Polish Academy of SciencesMazovia, Warsaw