The effect of environmental stimulation on the development of behaviour in pigs

Abstract

Eight pairs of litters were observed during Week 4, Week 7 and Week 18. One litter of each pair was kept under barren conditions and the other under enriched conditions during the whole observational period. Enriched pens were supplied with straw, logs and branches. The pigs were weaned at Week 5. Behavioural time budgets and frequencies of the elements were computed as well as an analysis of sequences. The pigs in the enriched pens spent much time in rooting, biting and chewing the provided material, while the pigs in the barren environment rooted, bit and chewed the floors and walls of the empty pen. At Week 4 the pigs in the barren environment spent 39% of all scans in manipulating the udder of the sow as compared with 22% for the pigs in the enriched pen ( P < 0.01). During the whole observational period they spent on average 26% of all scans in rooting floor and walls as compared with 3% for the pigs in the enriched pens ( P < 0.001). Pigs from the barren environment had higher frequencies of biting floor and walls ( P < 0.001), nudging littermate ( P < 0.05) and tailbiting littermate ( P < 0.01). Analysis of sequences showed no direct behavioural transitions between rooting or biting/chewing material or floor and walls and manipulating littermate, but in several instances there were significant transitions between manipulating littermate and lying inactive. Enriching the environment reduced the frequency of a number of behavioural disturbances in the present study, but the presence of these activities even in the enriched pens suggests that enrichment of the pen is not a sufficient solution to these problems.