Effect of oxytocin-supplemented semen on fertility of sows bred by intrauterine insemination

Abstract

Objective: To determine the efficacy of supplemental oxytocin added to the semen dose immediately prior to an intrauterine insemination. Methods: During September 2002, mixed parity sows on two commercial farrow-to-wean units (3000 and 1500 PIC sows) were inseminated at their first estrus after weaning (weaned sows; n = 442) or at a repeat estrus following a previous failure to successfully conceive (repeat sows; n = 100), using either a cervical (199 sows) or intra-uterine AI catheter. For sows inseminated using the intrauterine catheter, the semen did (172 sows), or did not (171 sows), contain 5 IU oxytocin. Semen age at insemination varied from 2 to 8 days. Results: Farrowing rates and subsequent litter sizes were not affected by treatment. However, an interaction between treatment and the number of inseminations during estrus indicated a higher farrowing rate (P = .02) if oxytocin was included in the semen for sows bred only once. While semen age had no effect on litter size, semen age > 4 days was associated with a reduced farrowing rate (P < .05). Farrowing rates were lower (P < .05) for repeat sows (63.7%) than for weaned sows (84.9%), but litter size was not affected. Implications: The use of intrauterine insemination does not improve fertility of sows. Inclusion of oxytocin in extended semen may benefit sow fertility when breeding management may otherwise result in a smaller sperm cell reservoir in the oviduct.