The effect of group housing on feeding patterns and social behaviour of previously individually housed growing pigs.

Group housed pigs make less frequent feeder visits of longer duration, and eat at a faster rate than pigs housed individually. They also have lower growth rates which may be due to elevated stress levels resulting from changes in the concentrations of hormones, such as cortisol and adrenaline associated with aggression and social stress. The aim of this experiment was to investigate the effects of grouping on feeding pattern, time budgeting and the social behaviour of pigs kept as individuals from weaning until grouping. In total, 12 Large WhitexLandrace male pigs (four pigs per block) mean (+/-S.E.) start weight 22.5+/-0.7kg were housed individually for 3 weeks (Period 1) after which in two replicates (Blocks 1 and 3), pigs were combined into a group of four (Period 2) before being returned to individual housing for a further 3 weeks (Period 3). In Block 2, the four pigs remained as individuals across periods but were moved between pens at the end of Periods 1 and 2 to account for any pen effects. Feeding pattern and food intake were recorded throughout and pigs were weighed three times a week. Video recordings and live behavioural observations were made to record time budgets and social behaviour. Grouped pigs made less visits to the feeder in Period 2 than when they were housed individually in Periods 1 (P<0.001) and 3 (P<0.01). Visit duration was longer in Period 2 than in Periods 1 (P<0.01) and 3 (P<0.05). Food intake and weight gain were greater in Period 3 than in Periods 1 and 2 (P<0.001 and P<0.01, respectively). There were no significant effects of moving pigs between pens in Block 2 on feeding behaviour and timebudgets. In Period 2, grouped pigs slept more (P<0.01) and spent less time feeding (P<0.01) and rooting (P<0.01) than in Periods 1 and 3. The frequency of aggression decreased over time from mixing (P<0.001). Possible explanations for the changes in feeding behaviour when pigs are moved from individual to group housing are competition, group cohesion, or that the high frequency of feeder visits when the pigs are housed individually is a consequence of a lack of social stimulation. Of these different possibilities, the results suggest that group cohesion is most likely to have been causal in the observed changes in feeding behaviour.

Diversity of behaviour during novel object tests is reduced in pigs housed in substrate-impoverished conditions.

Modern intensive farming conditions lack the diversity of substrates present in more natural environments and offer young animals fewer opportunities for interaction. Evidence exists that this may affect the organization of interactive patterns of behaviour, but shifts in behavioural diversity have not been measured directly. We investigated the effect of the substrate in the home pen on the diversity of behaviour in young growing pigs, Sus scrofa. Over 5 months, 26 pigs were housed singly in either substrate-impoverished (SI) or substrate-enriched (SE) conditions. Once every month we recorded the behaviour of these pigs in detail both in the home pens and in two novel object tests. In addition, we calculated the diversity of behaviour shown by SI and SE pigs in the home pen and in the novel object tests, using a relative behavioural diversity index. In the two novel object tests, SI pigs were less mobile than SE pigs and focused their behaviour on particular substrates. In addition, SI pigs showed less diverse behaviour than SE pigs. Our results show that the less diverse behaviour of SI pigs previously recorded in their home pens persists under novel conditions, supporting the hypothesis that substrate-impoverished housing conditions structurally affect the organization of behaviour in young growing pigs. Copyright 2000 The Association for the Study of Animal Behaviour.

The effect of delayed feeding on the post-feeding behaviour of sows.

Previous research into oral persistence in pigs has shown that the relationship between motivation and performance of stereotypy is not a simple one, and that non-specific motivational factors such as arousal may be important. For chronically food-restricted sows the time before food arrives is characterised by increasing excitement and arousal which may be carried over into the post-feeding period facilitating the performance of persistent oral behaviour. To investigate this possibility, arousal was manipulated by delaying feeding. Five and 15 min delays were used and sows experienced delayed feeding 1 day in every 4. Principal components analysis (PCA) was used to group the behaviour data into two factors, ACTIVITY/CHEW and NOSE/ROOT/PEN and these scores were then analysed using ANOVA as well as the appropriate individual behaviours. The delay of feeding increased the rate of eating, presumably reflecting increased arousal (P<0.05). ACTIVITY/CHEW scores were highest in 5 min delay sets, and an interaction between day of set and delay length indicated that ACTIVITY/CHEW scores peaked on different days within a set (P<0.05). Time spent chewing was highest on the day of delay (P<0.05), while standing was highest in days 1 and 2 post-delay (P<0.05). The NOSE/ROOT/PEN scores were lower on the day of delay than on other days (P<0.05), and were lowest in the first delay set than in sets later in the trial (P<0.01). It appeared that increasing arousal in the pre-feeding period does affect activity and oral behaviours in the post-feeding period. However, some of the effects appeared in a more extended and diffuse manner, perhaps due to the general disturbance created by the experimental regime and the sows' experience of long-term food restriction.

The spontaneous qualitative assessment of behavioural expressions in pigs: first explorations of a novel methodology for integrative animal welfare measurement.

Qualitative assessments of behaviour integrate and summarize the different aspects of an animal's dynamic style of interaction with the environment, using descriptors such as 'timid' or 'confident'. Although such qualitative terms are widely used in the study of animal temperament and personality, their use in relation to questions of animal welfare has yet to be formally explored. The terms used in integrative assessment (e.g., content, distressed) tend to have expressive, welfare-related connotations, and lie at the heart of the lay public's concern for animal suffering. For this reason they are frequently dismissed as 'anthropomorphic' and unscientific. However, in theory it is possible that these terminologies reflect observable aspects of behavioural organization. They may therefore be liable to scientific analysis, and be of use as integrative welfare measurements. A first step in investigating this hypothesis is to examine the inter-observer reliability of assessments of behavioural expression. This study investigated the extent to which 18 naive observers showed agreement when given the opportunity to qualitatively describe, independently and in their own words, the behavioural expressions of 20 individual growing pigs. Pigs were brought singly into a test pen and given the opportunity to interact with a human squatting in the centre of the test pen. Observers were instructed to first observe each pig and then to write down terms which adequately summed up the emergent qualities of that pig's behaviour. Data thus consisted of 18 sets of individually generated descriptive terms, attributed to 20 pigs. This procedure was repeated a month later with the same observers but using a new group of 20 pigs. To analyze the resulting 36 sets of descriptive terms, pigs in each set were given a score for each term. This score was either 0 (term not used for that pig) or 1 (term used for that pig). These data were analyzed with Generalized Procrustes Analysis (GPA), a multivariate statistical technique which finds a consensus between observer assessment patterns (the 'pig consensus profile'), and provides a measure of observer agreement. Results show that for each group of 20 pigs, the 'pig consensus profile' differed significantly from an analysis of the same data in randomized form (p<0.001), indicating that the consensus profiles were not artifacts of the GPA procedures. It can therefore be concluded that observers showed significant agreement in their spontaneous assessment of pig expressions, which suggests that these assessments were based on commonly perceived and systematically applied criteria. The extent to which these shared criteria reflect observable aspects of behaviour now requires further study.