Behavioural diversity and regrouping strategies in pigs

Abstract

The following studies were designed to gain a better understanding of individuality, social stress and behavioural development in domestic pigs. The first study used a series of behavioural observations and tests to assess the individuality of, and effect of regrouping stress on, 89 pigs. The studied factors were "approachability", "exploration," and "aggression". Regrouped pigs took longer to approach a novel object and human during a novel arena test (NAT) (P=0.01). The second study used the NAT to classify 222 pigs, as either slow (83 180 s), medium (32-79 s) or fast (0-27 s) to approach a human. Pigs were sorted into groups of all slow pigs (uniform slow), all fast pigs (uniform fast) or slow, medium and fast pig (diverse). Intact litters served as the control. Pigs in intact litters took less time to approach in the NAT (9.3 versus 28.6 ± 3.03 s; P=0.02), fought less (0.45 versus> 3.61 ± 0.45 fights/pig/hour; P