The influence of sow behaviour on piglet mortality due to crushing in an open farrowing system

The objectives of this study were to establish what changes in posture by s ows carried a high risk of piglet crushing in a group farrowing system duri ng early lactation and also to determine what factors influenced the risk o f crushing during lying down. A total lf 24 Large White x Landrace sows wer e studied during the first 7 days of lactation in a group farrowing system. Cross-fostering was not carried out so as not to influence behaviour. Dead piglets were removed and cause of death ascertained from external observat ion and post-mortem examination. Sow and piglet behaviour was video-recorde d continuously. A total of 268 piglets were born alive, with 67 liveborn pi glets subsequently dying during the 7-day experimental period, 50 as a resu lt of crushing. A total of 7425 posture changes were analysed and 11 types of posture change were identified, the most dangerous being lying down from standing and those involving swapping sides, or rolling over, whilst lying . Dangerous events during lying down were more likely to occur (1) in the fir st 24 h after farrowing, (2) when the sow lay down in the middle of the pen , (3) when the sow lay down without carrying out much piglet-directed pre-l ying behaviour and (4) when the piglets were spread out but near to the sow . the amount of pre-lying behaviour decreased over time and crushing mortal ity also decreased. The results confirm that he piglets are most vulnerable to crushing during the first 24 h of life, when they are spending much of their time near the udder and have relatively poor mobility. co-ordination of behaviour between the sow and her litter is important to reduce the risk of crushing. It is also important that the design of open farrowing system s incorporates knowledge about how crushing deaths occur in order to improv e piglet welfare.