Peat as environmental enrichment for piglets: The effect on behaviour, skin lesions and production results

The aim of this study was to examine whether the provision of small amounts of peat to piglets would influence behaviour and production. At approximately 5 days of age, nine litters received a tray of peat as enrichment, while nine others did not. All piglets had access to solid feed, which was used to compare substrate-directed behaviour. Piglets were weaned at week 4, and half of the pens in the nursery again received peat. The other half did not. This resulted in the following experimental design: peat/peat (PP), peat/no peat (PN), no peat/peat (NP) and no peat/no peat (NN). Each pen was observed for 4 × 1 min in the morning and also in the afternoon. During every minute the behaviour of each piglet was recorded continuously. The main behavioural categories were: foraging, exploration, playing, locomotion, resting, sleeping, biting and fighting. At 9 weeks of age the pigs were moved to the fattening unit, where no peat was provided. However, observations continued until the pigs reached slaughter age, i.e. until about week 24. Production results (weight, weight gain) and skin lesions were recorded from start to end. Piglets with access to peat performed foraging behaviour significantly more often than piglets without peat (P < 0.0001). After weaning, the results suggested a greater influence of present enrichment than previous experience in the farrowing pen. NP and PP piglets showed significantly less manipulation of pen mates (P < 0.005), less fighting (P < 0.001) and less inactivity (P < 0.0001). No effect on fighting or manipulation of pen mates was found in the fattening phase. Sleeping was observed more in the NP and PP groups (P < 0.05). Lying was seen less in the NN group than in the other treatment groups (P < 0.0001). No treatment effect was found on the frequency and severity of skin lesions. Weaning weight of P piglets did not differ from that of the control piglets (N). At the end of the weaning phase, PP piglets had a higher weight than NN piglets (P < 0.05). PP piglets also had a higher weight gain during weaning than NN and NP piglets (P < 0.05). The results suggest that providing small amounts of peat to suckling and weaner pigs could be an effective enrichment strategy to increase explorative behaviour and possibly reduce aggression time post weaning. It also had a beneficial effect on weight and weight gain of piglets. The removal of the peat during fattening led to more inactive behaviour, and differences in aggressive behaviour were no longer significant. Hence, a long term effect of peat supply was not observed.