The effects of straw bedding on the feeding and social behaviour of growing pigs fed by means of single-space feeders

Single-space feeders used in pig selection may favour those pigs which control access to the feeder. This was not the case when straw bedding was provided (Nielsen et al. 1995). However, straw may have modified behaviour and masked the effects of aggression. Therefore an experiment was conducted to examine the influence of straw bedding on behaviour and performance of pigs fed via a single-space feeder. The food intake, growth rate, feeding and social behaviour of 8 pens of 10 pigs (start weight 40 kg) with or without straw (4 pens/treatment) were recorded over a period of 35 days. Food was supplied by one single-space computerised feeder in each pen and this equipment provided records of feeding behaviour. Social behaviour and activity was observed by video recording on two occasions in week 2 and week 4 of the experiment. Each pen had an enclosed kennel. The provision of straw increased the number of visits to the feeder (13.11 vs. 9.22; P < 0.05) and these were of a shorter duration (4.34 vs. 6.18 min; P<0,05). The pigs on straw had a higher growth rate than those without (803 vs. 741 g/d; P < 0.05). Pigs with straw had a lower proportion of observations in the kennel (0.470 vs. 0.683; P < 0.001) and spent less observations lying (0.765 vs. 0.806; P < 0.05). The number of aggressive incidents initiated was higher with straw (14.8 vs. 8.8; P < 0.05). The modified feeding pattern with straw may have been due to a higher general level of activity or a combined effect of low ambient temperature and the position of the feeder relative to the kennel. Thus this effect of straw may be confined to cold environments. (C) 1998 Elsevier Science B.V. All rights reserved.