A quantitative and qualitative approach to the assessment of behaviour of sows upon mixing into group pens with or without a partition

Abstract

The behaviour of intensively managed sows is influenced by the design of their housing, with the physical structure of the pen affecting how sows spend their time. The first hour after unfamiliar sows are mixed into group housing is considered important in terms of their welfare due to high levels of aggression as they develop a hierarchy and investigate their new surroundings and pen-mates. This study compared the behaviour of sows on a commercial piggery at the point of mixing into 20 group pens (n = 15–18 sows each group), where half the group pens had a concrete partition (a short wall, 2 m long and 1.6 m high) running through the middle of the pen, and half did not have the partition. We predicted that the partition would improve the expression of behaviours during the first hour after mixing. Sows were filmed for 70 min post-mixing and the footage was analysed using quantitative behavioural profile for eight behavioural categories (i.e. time budgets). We found no significant differences in the incidence of aggression, but found less investigative behaviour for sows in pens with the partition; these sows also lay down sooner compared with sows in no-partition pens, and stopped eating/searching for food sooner. The difference between pen designs was most evident at 50–60 min post-mixing, and therefore we compared the behavioural expression of the sows using qualitative behavioural assessment for this time point. There was significant inter-observer reliability among the 17 observers, with 60.02% (P < 0.001) of the variation in their scoring using the Free Choice Profiling methodology explained by the consensus profile. Sows in partition pens were scored as more ‘calm/relaxed’ compared with sows in no-partition pens, which were scored as more ‘aggressive/tense’. There were also significant correlations between the time budgets and behavioural expression scores, with groups of animals described as more ‘aggressive/tense’ also showing more walking, aggression, and avoidance, but less lying. The sows described as more ‘sleepy/bored’ showed more lying and sitting. This study shows that even a subtle difference in housing design (in this case, retention of a concrete partition) can make a significant positive difference to the demeanour and activity patterns of sows. Identifying housing designs that have positive welfare outcomes can inform pen design and construction, and is particularly relevant where housing is being converted (e.g. from single pens to group housing) and decisions must be made around whether or not to keep existing structures.