Searching for difference in behavioural response of piglet groups subjected to a novel situations.

Individual difference in animal behaviour could clarify the differences in stress coping style, which have consequences in production, health and welfare. If differences in behaviour reflect coping characteristics, then behaviour in one situation should predict behavioural reactions in other situations and at other times. The Backtest (BT), the Open Field (OP) and the Novel Object (NO) tests have been used to identify individual reaction patterns in pigs and to measure parameters that previous studies showed to be correlated to the coping strategies of animals. The BT allows classifying piglets in two different "coping styles": high-resisting (HR), which adopt a (pro) active coping style and low-resisting (LR), which seem to behave as passive (or reactive) coopers. In previous researches subjects were tested singularly, so the aim of this study was to investigate if differences between HR and LR could be detected when piglets are tested in group. A total of 132 piglets were subjected to BT and then they were housed in group of four individuals for a total of 12 HR‟s boxes, 12 LR‟s boxes and 9 mixed boxes (2 HR and 2 LR piglets). At the age of 44 days piglets housed in the same box were subjected all together to OP and NO. We found difference in exploration time (p<0,03) during OP and in aggressive behaviour frequency (p<0,03) during NO; both of them were higher in LR than in HR piglets. We did not find any other relation between results of Backtest and reactions in the open field and novel object tests. Our results suggest that differences between HR and LR piglets involves few behavioural occurrences when animals were subjected in group to novel situations.