Influence of repeat-service and weaning-to-first-service interval on farrowing proportion of gilts and sows

The present study was performed to evaluate different components of reproductive failure after service under a tropical climate and to investigate the influence of repeat-service and delayed wean-to-service interval (WSI) on subsequent fertility in gilts and sows. The study was conducted in four commercial swine breeding herds in the northeastern part of Thailand. Data were collected during a 3-year period from July 2005 to June 2008. A total of 30,058 insemination records from 9037 gilts and sows was included. On average, the farrowing proportion (FP) was 81.9% and adjusted FP (excluding gilts/sows culled after service) was 85.3%. The reasons for the failure to farrow included return-to-oestrus 9.4%, abortion 1.7%, not being pregnant 1.0% and not-in-pig 2.0%. Non-repeat-service females had 83.7% FP, while those that experienced repeat-serviced for 1, 2 and ≥3 times had 71.2%, 57.7% and 43.4% FP, respectively (P < 0.001). The seasonal influence on FP was observed in non-repeat-serviced females, but not in those that experienced repeat-service. Sows mated during 0–6 days after weaning had 86.8% FP, while those mated 7–10, 11–20 and 21–60 days after weaning had 78.9%, 78.9% and 78.4% FP, respectively (P < 0.001). It is concluded that repeat-service in gilts/sows resulted in a 12.5% decrease in FP. Sows returning to oestrus later than 6 days after weaning had 7% lower FP than sows mated within 6 days after weaning.