Short- and long-term effects of eight enrichment materials on the behaviour of finishing pigs fed ad libitum or restrictively
Publication Type: |
Journal Article |
Year of Publication: |
2013 |
Authors: |
Bettina Zwicker, Lorenz Gygax, Beat Wechsler, Roland Weber |
Publication/Journal: |
Applied Animal Behaviour Science |
Keywords: |
behaviour, enrichment, exploration, feeding, motivation, pigs |
ISBN: |
0168-1591 |
Abstract:
In a semi-natural environment, a lot of the daily activity of pigs is spent in exploratory and foraging behaviour. Providing enrichment material attractive to the pigs both over the short and long term is therefore important in intensive housing systems. This study aimed to investigate the effect of four types of point-source enrichment materials and four types of litter on the behaviour of finishing pigs. In experiment 1, pigs were offered cut straw or cut straw enriched with maize kernels as litter on the lying area, as well as a cylindrical dispenser filled with a compressed straw block or a straw rack filled with cut straw. In experiment 2, chopped straw or chopped Miscanthus giganteus was provided as litter on the lying area, along with a straw-pellet dispenser or bark compost in a trough. In both experiments, 96 finishing pigs with undocked tails were housed in groups of six pigs in pens with partly-slatted floors. Half of the groups were fed restrictively, the other half ad libitum. Every three weeks, the enrichment materials were replaced. Exploratory behaviour directed towards the enrichment material, the pen equipment and pen mates was videorecorded and analysed by means of one-minute focal-scan sampling on the second and eighteenth day after provision of a new enrichment material. Data were analysed using linear mixed-effect models. In both experiments, the frequency with which the enrichment material was explored was influenced by the interaction of type of material and day (p < 0.001). On the second day after provision of enrichment, the favoured material was cut straw enriched with maize kernels in experiment 1, and the straw-pellet dispenser in experiment 2. On day 18, straw as litter with or without maize, the straw rack, chopped straw, chopped Miscanthus giganteus and the pellet dispenser were used with a similar, and still relatively high, frequency. The least-explored materials were the straw block and bark compost. In both experiments, pigs fed ad libitum explored the materials less than half as frequently as those fed restrictively (p < 0.001). Manipulation of the pen showed a pattern inverse to that of manipulation of the material, but a similar pattern with respect to feeding regime. Materials had no discernible influence on the manipulation of pen mates. In conclusion, our results indicate that both the point-source enrichment and the litter materials provided constituted adequate enrichment for small groups of finishing pigs.