Effects of early play experience on play behaviour of piglets after weaning

Abstract

We hypothesised that play experience gained by piglets during early ontogeny would affect their ability to cope with weaning stress. Specifically, we predicted that (i) weaning would initially result in low play levels and (ii) better coping ability would be reflected by a more rapid increase in play levels with time after weaning. We manipulated play experience in three pre-weaning treatments (1) Obstacles (play with littermates restricted by barriers throughout the 2.1 m×1.8 m home pen and a 1.7 m×1.5 m observation pen into which each litter was placed during seven 30 min periods between day 8 and day 23), (2) Littermates (unobstructed play with littermates in home pen, and observation pen), and (3) Aliens (unobstructed play with littermates in home pen, and with littermates and non-littermates in observation pen). We expected the treatments to increase coping ability as follows: Aliens>Littermates>Obstacles. Two males and two females from each of eight litters per treatment were housed together after weaning at day 24. On days 1, 3 and 5 after weaning, they were placed in the (unobstructed) observation pen for 30 min. Data were analysed using mixed model repeated measures analysis of variance on log-transformed data. In all three play categories studied (locomotor play: scampers, pivots, head tosses, flops and paws; social play: non-injurious bites, levers, and “push-overs”; and transitions to self-handicapping positions: sitting, kneeling or lying), the frequency of play behaviour was lower on day 1 after weaning than on the day before weaning, and increased to pre-weaning or higher levels on days 3 and 5 after weaning ( P<0.001). On day 3 after weaning, the frequency of social play behaviour was in the predicted direction (Aliens>Littermates>Obstacles) resulting in a significant treatment×time effect ( P<0.05). Our results indicate that the depression of play after weaning is profound but transient. We found evidence that early play experience before weaning had some effect on social play after weaning, but not on total locomotor play or transitions to self-handicapping postures in the first week after weaning.