A systematic approach towards developing environmental enrichment for pigs

Abstract

Environmental enrichment is often implemented without considering the requirements of the animals within their environment and without specifying desired functional behaviours. An approach towards the development of species-specific environmental enrichment for pigs is presented here, which attempts to avoid introducing enrichment on an intuitive basis and instead uses behavioural observations of interactions with enrichment to analyse which characteristics of objects stimulate exploratory behaviour in pigs. The intensity of interactions of 222 groups of three weaner and 222 groups of three grower pigs with 74 different objects were studied during 5 days in order to find the characteristics that the favoured objects had in common. Each object was described using 28 descriptors and these were correlated with object-directed behaviour scores obtained from videos. Multiple Stepwise Regression analysis identified which of the characteristics played a major role in determining the level of object-directed behaviour. The main characteristics emerging on day 1 (odorous, deformable, not rootable, not attached, chewable) reflected the initial attractiveness of an object. The main characteristics emerging on day 5 (ingestible, destructible, contained, not particulate, not rootable) reflected sustained attention towards an object. These results underline the importance of enrichment for pigs which stimulates foraging and explorative behaviour. The approach proved to be a useful tool and may be used for other species to assess the importance of different environmental features. The optimal combination of the important characteristics can be used to design functional environmental enrichment, which takes into consideration species-relevant requirements.