The associations between weaning-to-estrus interval and sow efficiency

Michael R. Wilson, BVSc, PhD; Catherine E. Dewey, DVM, PhD

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We conducted two retrospective studies, one involving 2800 sows in a single herd in Australia over 3 years, the other involving 22,715 litters from 112 herds in Ontario, Canada over 5 years. Litter size and farrowing rate were studied individually and combined as an index--pigs produced per mated female (PPMF)--to investigate how they relate to length of weaning-to-estrus interval. Litter size, farrowing rate, and PPMF) all decreased among sows mated on days 7-10 postweaning compared to sows mated either 3-6 days postweaning or 11-14 days postweaning. PPMF) was reduced by approximately 30% in that less-efficient period.Approximately 11% of sows were detected in estrus during the less-efficient period. Forty percent of parity-one sows with a weaning-to-estrus interval of 7-10 days also had weaning-to-estrus intervals of 7-10 days in parity two. If sows that came into estrus 7-10 days postweaning were not mated until their next estrus (between days 28 and 31), their efficiency at least equaled that of sows that came into estrus during the more-efficient interval. Almost 30% of the delay- mated sows came into estrus 7-10 days postweaning in their next parity. We discuss the dip in efficiency associated with the occurrence of estrus 7-10 days postweaning and compare it to the second-litter productivity drop described by other investigators.

RIS citationCite as: Wilson MR, Dewey CE. The associations between weaning-to-estrus interval and sow efficiency. J Swine Health Prod 1993;1(4):10-15.