Effect of estrogen formulation and site of deposition on fertility of artificially inseminated sows treated with human chorionic gonadotrophin to induce ovulation
Glen Cassar, DVM, PhD; Roy N. Kirkwood, DVM, PhD, Diplomate ECAR; Zvonimir Poljak, DVM, MSc; Robert Friendship, DVM, MSc, Diplomate ABVP
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Objective: To determine the effect of estradiol, either added to extended semen or deposited onto the vaginal mucosa, on the reproductive performance of artificially inseminated sows.
Materials and methods: At 80 hours after weaning, 227 mixed-parity sows received an intramuscular injection of 750 IU of human chorionic gonadotrophin (hCG) to induce ovulation. At 36 and 46 hours after hCG injection, sows exhibiting estrous behaviour (n = 198) were artificially inseminated with 3 x 109 spermatozoa in 80 mL extender. At the time of insemination, sows were sequentially assigned to receive 25 mg estradiol dissolved in the semen dose (E-semen; n = 66), 25 mg estradiol in an oil solution deposited onto the anterior vaginal mucosa (E-vag; n = 66), or no estradiol (Control; n = 66). Real-time ultrasound was used to determine pregnancy status 26 to 30 days after insemination. Pregnancy rates, farrowing rates, and subsequent total-born litter sizes were recorded.
Results: Pregnancy rates were 97.0%, 92.4%, and 90.9%, farrowing rates were 89%, 92% and 89%, and litter sizes were 11.1, 10.8, and 10.5, for E-semen, E-vag, and Control, respectively. Differences were not significant (P > .5). These data indicate no benefit from supplemental estradiol at the time of insemination. However, any effect may have been masked by an improved performance of all treatment groups relative to the herd's historical farrowing rate (75.7%).
Implications: The breeding of sows following a controlled induction of ovulation may have the potential to improve sow fertility. However, under these conditions, supplemental estradiol provided no significant further benefit.
Keywords: fertility, estradiol, semen, hCG
Cite as: Cassar G, Kirkwood RN, Poljak Z, et al. Effect of estrogen formulation and site of deposition on fertility of artificially inseminated sows treated with human chorionic gonadotrophin to induce ovulation. J Swine Health Prod 2004;12(6):285-287.
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