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

The use of traditional operant conditioning techniques to assess the behavi oural needs of farm animals has been criticised because presenting short re wards repeatedly may interrupt bouts of behaviour and thereby devalue the r eward. The two reported experiments (one including 12 calves and one includ ing 12 piglets) aimed to investigate if interruption of social contact affe cts social behaviour. In both experiments, animals were housed in pairs (on e 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 p ost-test period. Animals were separated for 24 h and then reunited for 24 I t in each period. In the test period, the first 42 min of contact after reu nification comprised 12 successive 3.5 min long periods separated by gaps. whereas in the pre- and post-test periods, the contact was continuous. Calv es sniffed and licked each other more when social contact was interrupted ( P < 0.01), but no effects of interrupting social contact were found for soc ial or locomotor play. In piglets, the test animals performed more flank pu shing of the companion (P < 0.01), and avoided the companion more (P < 0.05 ), when social contact was interrupted, while no effects of interruption we re found for parallel pressing, bites and head knocks, sniffing or locomoto r play. The results suggest that if social contact is interrupted in an ope rant conditioning set up, some elements of aggressive behaviour may be stim ulated in piglets. (C) 2001 Elsevier Science B.V. All rights reserved.