INFLUENCE OF PARITY AND TIME SINCE PARTURITION ON RESPONSIVENESS OF SOWS TO A PIGLET DISTRESS CALL

The responses of sows to playback of a recorded piglet squeal were evaluated in two experiments. In Experiment 1 the effects of sow parity (1, 2, 4 and 6) and time since parturition (1 or 2 days post-partum) on responsiveness were tested in a factorial experiment with 160 sows. Sows were slapped on the shoulder to make them stand and then the squeal was played back as the sow knelt prior to lying. There was no difference in responsiveness to squeal playback between Days 1 and 2 post-partum. However, sows were less responsive to general stimulation on Day 1 than on Day 2. They required more slaps to stand and knelt down again more quickly. Parity did not affect any of the variables measured, except reaction time. Parity 1 sows reacted more quickly to playback by either standing or lying than older sows. In Experiment 2 variation in responsiveness was measured over 20 days following parturition in 12 sows. Responses to squeal playback or a control of no sound playback were tested when the sow knelt following normal feeding at 08:30 or 10:30 h for 5 days following parturition and then every third day until Day 20 post-partum. Sows took longer to lie down and had higher response scores after playback of the squeal than the control of no playback. Lying latency was not affected by day number, but there was a greater response score to the squeal on Day 1 than on other days. The results suggest that responsiveness to piglet distress calling is an innate response, which is not influenced by previous exposure to piglet squeals or previous experience of maternal behaviour. Variation in sow responsiveness post-partum indicates that the sow is capable of responding to distress calls at any time post-partum, but is most receptive to piglet stimuli within the first 2 days post-partum.