Observations on the pre- and post-weaning behaviour of piglets reared in commercial indoor and outdoor environments

A number of behavioural problems are associated with weaning piglets including belly nosing, ear and tail biting, and low intake of solid food. These appear to be less pronounced in piglets reared on outdoor systems, which initially consume more solid food and show less belly nosing and aggression than comparable indoor-reared piglets. The objective of this study was to investigate how these differences in post-weaning behaviour relate to the piglets’ pre-weaning behaviour in the two rearing environments. The study was carried out at a commercial pig unit, where piglets of the same genotype are born into conventional indoor or outdoor farrowing systems. In the intensive system, sows were singly housed prior to farrowing in crates and their piglets received a solid ‘creep’ food prior to weaning. On the outdoor system, sows were allowed to build straw nests in arks for farrowing and both sow and piglets had access to pasture. Indoor and outdoor piglets were weaned at 24 (±3) days of age and mixed in straw-yard housing with access to a solid food. Prior to weaning, teat-directed activity was more common in indoor piglets than outdoor piglets. Outdoor piglets performed more rooting, standing and locomotion and were seen chewing the sows’ roll-nuts. Following weaning, outdoor-reared piglets performed more feeding and rooting, and less fighting than indoor-reared piglets. This study supports previous findings that undesirable activities such as fighting are less common in piglets weaned from outdoor systems, even when mixed with indoor piglets. In addition, outdoor-reared piglets were more likely to exploit solid food even though they did not have access to creep food prior to weaning.