Abstract
Objective: To determine the effect of porcine luteinizing hormone (pLH) on time of ovulation and subsequent fertility to single or double artificial insemination (AI). Materials and methods: In Experiment One, 17 sows received equine chorionic gonadotropin (eCG; 600 IU) intramuscularly (IM) at weaning, then 5 mg pLH IM 80 hours later to induce ovulation. Time of ovulation was determined using transrectal real-time ultrasonography. In Experiment Two, 567 sows were assigned to five treatments: no hormone treatments, AI am and pm day 5 after weaning; eCG at weaning; AI am and pm day 5 after weaning; pLH 80 hours after weaning, AI 36 and 44 hours later; eCG at weaning, pLH 80 hours later, AI 36 and 44 hours after pLH; eCG at weaning, pLH 80 hours later, AI 36 hours after pLH. Results: Time from pLH to ovulation was 38.2 +/- 2.8 hours (range, 34.25 to 42.5 hours). Of the 567 weaned sows, 530 (93.5%) were bred and 403 (76.0%) farrowed. There was no effect of eCG on subsequent fertility. Farrowing rate was higher (P < .01) for sows receiving eCG followed by pLH at both insemination frequencies. Litter size was unaffected by treatment. Implications: A protocol of eCG-induced estrus and pLH-induced ovulation allows for predictable timing of ovulation and optimal timing of insemination relative to ovulation. The degree of predictability allowed for maintenance of fertility to a single, fixed-time insemination.
Published Version
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