The effect of combining different environmental enrichment materials on enrichment use by growing pigs

• Published in: Applied animal behaviour science Vol. 144; no. 3-4; pp. 102 - 107
• Main Authors: Guy, Jonathan H., Meads, Zoe A., Shiel, Robert S., Edwards, Sandra A.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.03.2013
• Subjects: body weight; Enrichment; environmental enrichment; European Union; foraging; Habituation; laws and regulations; Methodology; Novelty; Pig; sawdust; sisal; swine; wood shavings; Enrichment; Methodology; Novelty; Habituation; Pig
• ISSN: 0168-1591; 1872-9045
• DOI: 10.1016/j.applanim.2013.01.006

EU legislation requires that growing pigs are provided with suitable materials that satisfy their needs for investigation and manipulation. Although commercial pig keepers have tried a variety of different enrichment materials and methods of presentation, the benefits to the pig have not always been clear. The aim of this paper was to determine: (1) the extent to which provision of separate enrichment materials gives predictable additive increases in occupation time, (2) whether there is consistency in the relative use of different enrichment materials over time and, if so, and (3) whether a rapid methodology could be used to evaluate the relative enrichment value of a particular material for growing pigs. A total of 36 growing pigs (mean liveweight 36kg) were used, housed in 12 groups of 3 in part-slatted pens in a controlled environment building. Four enrichment materials with different properties were compared: two hanging objects suspended above the pen (sisal rope, R and metal chain, C) and two foraging substrates provided in a trough (sawdust, S and wood shavings, W). The materials were presented in pairs, in all six combinations (CR, CW, CS, RW, RS and WS) with each group of pigs exposed to one combination of materials for five days followed by the other two materials for a further five days. Time interacting with each enrichment material was determined on a per pen basis. The results showed that although the pigs very quickly habituated to all of the enrichment materials, they spent a greater proportion of time interacting with some materials than others (e.g. rope: 0.17, sawdust: 0.04; P<0.001). Pairing the four different enrichment materials in different combinations affected the relative proportion of time pigs spent with different materials. For example, pigs spent relatively more of enrichment-directed time with the chain when it was paired with sawdust compared to when it was paired with shavings (0.82 versus 0.46 of total enrichment-directed time; SEM 0.078, P<0.01). However, for all materials there was consistency in the absolute level of interaction over the 5-day test period, with proportion of total time engaged with a given material not significantly different in different pairings. It is concluded that, for the materials used in the current study at least, use of enrichment materials is additive and relatively independent. The findings of this study suggest that a simple paired test, where any potential new enrichment material is presented alongside a material of known occupational value (to avoid any bias due to habituation, the test animals should be naïve to both enrichment materials), could be used to predict the enrichment value of the new material.