THE EFFECT OF PLAYBACK VOLUME AND DURATION ON THE RESPONSE OF SOWS TO PIGLET DISTRESS CALLS

The effect of variation in playback volume and duration on the responses of recently farrowed sows to a recorded piglet squeal was evaluated in two experiments. In Experiment 1 the squeal was played back at soft (76-77 dB), normal (84-86 dB) or loud (92-95 dB) volumes as the sow was kneeling prior to lying down. Sows took longer to lie down in response to loud playback than normal or soft playback, and were more likely to sit or stand in response to loud playbacks than normal or soft playbacks. In Experiment 2 the recorded squeal was played back at normal volume for 30, 60 or 120 s, together with a control of no playback. Sows took longer to lie down in response to sound playback compared with no playback, but there were no significant differences between the three durations. Similarly, sows were more likely to sit or stand in response to sound playback than no sound playback, but there were no differences between the three durations of playback. These results indicate that the important acoustic properties of a piglet distress call are its sudden onset and high intensity, and that prolonged calling by a piglet is unlikely to cause a sow to stand.