Effects of interrupted social contact on the social behaviour of calves and piglets

The use of traditional operant conditioning techniques to assess the behavioural needs of farm animals has been criticised because presenting short rewards repeatedly may interrupt bouts of behaviour and thereby devalue the reward. The two reported experiments (one including 12 calves and one including 12 piglets) aimed to investigate if interruption of social contact affects social behaviour. In both experiments, animals were housed in pairs (one test animal and one companion animal) in large pens with solid sides. The experiment included three periods a pre-test period, a test period and a post-test period. Animals were separated for 24 h and then reunited for 24 It in each period. In the test period, the first 42 min of contact after reunification comprised 12 successive 3.5 min long periods separated by gaps. whereas in the pre- and post-test periods, the contact was continuous. Calves sniffed and licked each other more when social contact was interrupted (P < 0.01), but no effects of interrupting social contact were found for social or locomotor play. In piglets, the test animals performed more flank pushing of the companion (P < 0.01), and avoided the companion more (P < 0.05), when social contact was interrupted, while no effects of interruption were found for parallel pressing, bites and head knocks, sniffing or locomotor play. The results suggest that if social contact is interrupted in an operant conditioning set up, some elements of aggressive behaviour may be stimulated in piglets. (C) 2001 Elsevier Science B.V. All rights reserved.