Investigation of the reward cycle associated with play behaviour in lambs
The aim of this study was to investigate if behaviour, ear positions and cortisol in lamb which were given access to play followed the different phases of the reward cycle of anticipation, consumption and relaxation. The study was done on 8 Dorset and 12 Dorset x Fine Wool uncastrated male lambs with an average age of 10 weeks. The lambs were housed pairwise in litter pens (2 x 3 m). Pairs of lambs were taken to a play arena (5.9 x 5.5 m) three times a week during five weeks (first week for learning). They were then first kept in a holding pen where they could look into the play arena for 5 minutes and thereafter released for 20 minutes in the play arena which had a ball, two chains and a tunnel. They walked back to their home pen and were observed for 6 minutes thereafter. Observations of behaviours were made as frequency per minute in all three places. Four different ear postures were recorded in the three places to study emotional valence in lambs. During the last week saliva sampling was done for cortisol analyses during the last week; one sample in the home pen before play and another in the home pen after play. Lambs showed significantly more anticipatory behaviour than non-anticipatory behaviour in the holding pen (p