Effects of attention and rewarded activity on immune parameters and wound healing in pigs

Challenging animals with a demanding situation they are able to cope with and where they are rewarded may be a source of positive emotions and possibly of increased welfare. In order to test if this results in changes of immunological parameters and wound healing, 56 pigs (7-20 weeks of age), housed in groups of 8 animals each, were successfully trained to recognize and localize an individual acoustic summons and to receive a small portion of feed as a reward. Immune reactions and the development of a standardized biopsy wound were compared to values of conventionally fed control groups of equal size and animal-to-feeding-place ratio (2:1). In the experimental animals a significantly higher concentration of IgG as well as an increased in vitro T-cell proliferation to ConA but a reduced LPS-induced proliferation of B-cells was found, while basal salivary cortisol concentrations were similar. Wound development was better in the experimental animals as measured by the area of the inflammatory corona. It decreased more rapidly in the experimental animals since the 5th day after biopsy and was significantly smaller than in the control groups. We conclude that environmental enrichment by equipment provoking attention and cognitive activity which is rewarded by feed may play a beneficial role for physical welfare of intensively housed pigs.