Franchi, G. A., Larsen, M. L. V., Kristoffersen, I. H. et al. 2023. Play behaviour positively relates to weight gain, feeding behaviour and drinking behaviour in weaner pigs (Sus scrofa). Applied Animal Behaviour Science 259, 105836.

Engagement in play behaviour has been associated with the presence of positive affective states and, thus, proposed to be an indicator of positive animal welfare. However, the interpretation of play in animals remains challenging due to the complexity of motivating factors. Accordingly, we aimed to clarify whether Yorkshire × Landrace weaner pigs would engage more in play behaviour the more well-nourished they were by examining the effects of weight gain, feeding behaviour, and drinking behaviour on two types of play behaviour [locomotor-rotational play (LOC) and social play (SOC)]. In total, 24 litters [pigs/litter: (mean ± SD) 13 ± 2] raised under conventional husbandry conditions were included in this study. Each pig was manually weighed within 24 h of birth and on days − 7, 0, 1, 2 relative to the weaning day (day 0) at approximately 26 days of age. All behavioural measures were registered via video at individual level. Visits to feeder and drinker were registered from 07:00 h to 21:59 h on days − 1 and 1 using 2-min interval instantaneous sampling. The proportion of visits to each resource was calculated by dividing the number of scans visiting the resource by the total number of daily scans. The latencies to visit the feeder and drinker within the first 24 h post-weaning were continuously recorded. Both LOC and SOC were registered between 14:00 h and 22:00 h on days − 1, 1 and 2. Both before and after weaning, heavier pigs spent more time performing LOC. Before weaning, heavier pigs spent more time performing SOC. Proportion of visits to the feeder positively related to LOC after weaning. On the day before weaning, the proportion of visits to the drinker positively related to LOC. No clear relationships between the latency to feed and drink after weaning and play behaviour were found. Our study supports the hypothesis that motivation to play is higher when animals are in more stable conditions, e.g., well-nourished, and healthier than under suboptimal conditions. However, the fact that the nutritional measures did not similarly affect LOC and SOC suggests that these two types of play behaviour may be differently affected by the weaning context and questions whether they have the same underlying motivation. This study represents a step toward the validation of play as a positive animal welfare indicator.