Effects of a nursing sound stimulus on performance of lactating sows and litters

The goal of this study was to determine an effective interval of playing a nursing sound stimulus. One hundred forty four lactating multiparous sows (Landrace; parity range: 2 to 7) and their litters (Landrace × Yorkshire) were divided into 3 block (48 each), each of which was randomly assigned to one of the four treatment groups including control which had no call stimulus (n = 12 each). The call of nursing and suckling, plus a click sound, were used as a nursing sound stimulus that was played in the intervals of 35 min (T35), 40 min (T40) and 45 min (T45) right after the first parturition in each experimental group until the day of weaning. Nursing sound stimuli did not affect the sow feed intake and back fat thickness loss. No differences were detected among treatments in the percentages of sows returning to estrus within 5 days after weaning and sows without crushed piglets. However, the piglets' weaning weight and daily weight gain in T35 and T40 groups was greater (p < 0.01) than the controlled piglets. These results suggest that a nursing sound stimulus can improve the performance of suckling piglets, and that 35 or 40 min interval of playing a nursing sound could be the effective sound stimulus for nursing sows.