Estrus and fertility in lactating sows and piglet performance as influenced by limited nursing

Seven trials were conducted with 126 sows and their litters to determine the influence of limited nursing (LN), starting on day 21 of lactation, on estrous activity and conception rate during lactation and on piglet performance. One-half of the sows in each of the first three trials were allowed to nurse their piglets four times daily for 30-min periods for 12 days. In the last four trials, half of the sows nursed their piglets four times daily for the first 3 days and then three times daily for 4 days (7-day limited nursing). The remaining sows in each trial were allowed to nurse their piglets in a normal manner. All piglets were weaned at the end of the LN period. Piglets were weighed at the start of the study, at weaning and at 14 days postweaning. Creep intake was measured during the LN period. In the first three trials, eight of the 26 LN sows were in estrus before weaning, whereas no control (C) sows were in estrus during lactation (P greater than .01). The average interval from weaning to breeding was 1.7 and 6.6 days for LN and C sows, respectively (P greater than .01). In the last four trials, five of 37 LN sows were in estrus before weaning, whereas no C sows were in estrus during lactation (P greater than .07). The average interval from weaning to estrus was 3.3 and 4.3 days for LN and C sows, respectively, (P greater than .05). Conception rate did not differ between trials or between treatment groups. Weight gain during the treatment period was lower and creep feed intake greater (both P greater than .01) for pigs reared by LN sows than for piglets reared by C sows. Weight gained after weaning was greater (P greater than .05) for piglets reared by LN sows than for those reared by C sows in the first three trials, but was similar for the two groups in the following four trials. Piglet death loss was similar for the two groups throughout the experiment.