Effect of earth as an additional stimulus on the behaviour of confined piglets.

Groups of 8 piglets were housed in flat-deck cages with slatted floors. Experimental cages were provided with a trough of sterilized earth, and the behaviour of focal individuals was recorded for comparison with controls. This replaced an earlier study, with which some of the results were combined. Records were analysed for frequencies and duration of certain activities, and first order sequence analysis was carried out. Experimental piglets rooted in earth for 4 to 8% of observations and also fed for longer. They spent less time sitting or lying. Aggression was reduced and there was a trend for experimental piglets to chew each other less. These differences suggested conditions were more favourable in experimental pens than control pens. However, there were few differences in first order behavioural transitions. Use of earth was not involved in sequences with activities such as feeding, drinking or lying as expected. It seems likely that in these circumstances earth did not act as a stimulus relevant to behavioural organization, but in some other way, with interest declining over time.