Piglets have difficulties with the abrupt changes at weaning associated with conventional pig production systems. Previously, it has been shown in rats that reward and announcement of reward counteracts impact of stress effects. In the present study, it was investigated if announcement of an environmental enrichment, more than enrichment alone, could facilitate play behaviour and reduce weaning-stress-induced behaviours such as increased aggression with subsequent increased injuries and increased social manipulative behaviours (i.e., tail biting, belly nosing, mounting). Twenty-four litters of conventional housed fattening piglets were kept under three different experimental conditions: sound cue (conditioned stimulus, CS) paired with an environmental enrichment (unconditioned stimulus, US) with a maximum delay between the CS and US of 30 s (CS-US paired) in which anticipatory behaviour develops; cue-environmental enrichment unpaired (CS-US unpaired) and no cue and no environmental enrichment (No CS-US). At two weeks of age the so-called 'anticipation procedure' started and ended two days after weaning. Growth, play, aggressive, social manipulative, eating and inactive behaviour, and injury rates were measured before and after weaning. Results of this study indicated that announcement of enrichment and not enrichment alone significantly increased play behaviour after weaning.

In this experiment, we investigated whether music can facilitate play behaviour in piglets after weaning, when that music had been presented preweaning as a contextual cue associated with access to a playroom. One group of piglets was given daily access to a playroom preweaning while music was played during the entire play period (Playroom group, n = 6 pens). The control group was daily exposed to the music as well, but this group was not given access to the playroom (NO Playroom group; n = 6 pens). It was hypothesized that replay of music post weaning (on post-weaning days W2, W3 and W6) would facilitate play behaviour above and beyond the previously reported effects of preweaning playroom exposure per se. The results confirm that music replay post weaning does facilitate play behaviour in the Playroom group. The results also showed that playroom exposure preweaning reduced the number of injuries post weaning (W1, W2 and W3). In contrast with our expectations, music replay also facilitated play behaviour in the control group, although significantly less so than in the Playroom group. The results are discussed in relation to the possibilities to use music as a tool to improve welfare in animal husbandry systems. #