Maternal infanticide in sows: Incidence and behavioural comparisons between savaging and non-savaging sows at parturition

Aggressive behaviour by newly farrowed sows towards their own offspring, known as savaging, occurs commonly in the domestic pig, with a significant impact upon both the agricultural economy and animal welfare. The aims of this study were to investigate the incidence and nature of this behaviour and to compare other behaviours between savaging and non-savaging sows around parturition in 226 F2 sows that were produced by two highly divergent pig breeds of Chinese Erhualian and western Duroc with significantly genetic difference on maternal behaviours and were raised at three different pig farms. Each of these sows was housed in individual 2mx2.5m pens with concrete floors. Three kilograms of fresh straw was provided to sows before parturition. Behaviour observations were made from 5h before parturition to 24h afterward using real time 1:0 sampling. Savaging sow was defined as an apparently deliberate attack on one or more piglets that resulted in the death, by biting, of at least one piglet. The incidence of savaging was: farm 1, 10.7% in gilts (n =103) and 5.3% at the second farrowing (n =94); farm 2, 14.6% (n =48) and 6.25% (n =16), respectively; farm 3, 6.8% (n =44) at the second farrowing and 3.2% (n =31) at the third farrowing. The incidence of savaging tended to be higher in gilts (P =0.058) although some savaging gilts were killed before their second litters. There was no effect of the different farms on incidence of savaging. Prepartum nest building behaviours were not a predictor for savaging, but savage sows had a greater frequency of posture change from before parturition through the expulsive phase. This restlessness included an increase in rearing behaviour and a reduced ability to lie down carefully without endangering piglets. We suggest that savaging is part of a more generalized behavioural pathology that includes increased excitability and is not specifically piglet directed.