Crushing of piglets by the mother sow (Sus scrofa)-purely accidental or a poor mother?

A sample of 59 healthy, hybrid (Landrace × Yorkshire) sows were video recorded from 2 days before until 4 days after farrowing. From this material, 11 that had not crushed any of their piglets ('Non-crushers') within the first 4 days after farrowing and 11 sows that had crushed two or more of their piglets ('Crushers') within the same time period, were selected for further behavioural tests and analysis. Sows that did not crush any of their piglets showed a more protective mothering style (i.e. performed more nest building activity, responded sooner on piglet distress calls, initiated nose contacts sooner after presentation of distress calls, nosed more on the piglets during posture change, were more restless when the piglets were taken away) and were socially more flexible (avoided conflicts to a larger extent) in a grouping situation than sows that crushed several piglets. Crushing as a cause of neonatal death in piglets is therefore highly related to mothering style.