Individual differences in the behaviour of sows at the nest-site and the crushing of piglets

Abstract

This study examines the relationship between individual differences in the behaviour of sows, Sus scrofa, and piglet mortality caused by crushing. Continuous 24-h video recordings were made of 11 loose-housed sows and their litters during parturition, and during the following 10 days. Each sow and litter were kept in a pen with a straw-bedded nest-site. Piglets were defined as in danger of being crushed if they were trapped by the sow's body or if they jumped aside in response to the lying down or rolling behaviour of the sow at the nest-site. An overall score (derived from five behavioural measures) of the quality of sow behaviour in relation to crushing was computed for each sow. This score was significantly correlated with the number of piglets in danger in each litter during the first 10 days after farrowing. The 11 sows were also scored with respect to their responsiveness to playbacks of piglet distress calls. Sows with a high responsiveness had fewer of their trapped piglets crushed. Both the score of the quality of sow behaviour and the score of the sows' responsiveness to piglet distress calls were significantly negatively correlated with the percentage of liveborn piglets (born several months before or after the present study) in which crushing was the primary cause of death. In conclusion, our results provide evidence that the occurrence of crushing is significantly related to individual differences in sow behaviour.