Evaluation of an ovarian synchronization scheme for fixed-time artificial insemination in wapiti.
The ovarian response to an empirically derived treatment protocol used commercially for fixed-time insemination in wapiti (Cervus elaphus) was evaluated by transrectal ultrasonography in hinds during transition into the ovulatory season. On September 29, hinds (n=7) were given an intravaginal progesterone-releasing device (CIDR-B, 1.9 g of progesterone) or left untreated (controls, n=9). Fourteen days later, hinds in the treated group were given 200 IU eCG and the CIDR was removed. Hinds in the control group ovulated randomly over a 15 day period. In the treated group, five hinds ovulated 3 days after eCG treatment, one ovulated 7 days after treatment, and one failed to ovulate by November 1. All extant dominant follicles ceased growth and/or began to regress within 2 days of CIDR placement. Two waves of follicular development were detected between CIDR insertion and removal; the first emerged 5.1+/-0.5 days after CIDR insertion and the second at 11.0+/-0.7 days. Serum progesterone concentration was 0.6+/-0.5 ng/mL (range 1.0-0.3 ng/mL) before CIDR placement, remained above 6 ng/mL during CIDR placement, and fell to 0.8+/-0.9 ng/mL after CIDR removal. In the control group, maximal luteal-phase progesterone concentration was lower (1.1+/-0.1 ng/mL; P<0.05) and emergence of the first follicular wave was more variable (P=0.05) than in the treated group. The protocol to synchronize ovulation was effective in 5/7 (71%) hinds, and 4/7 (57%) became pregnant and calved. The pregnancy rate (6/9) and calving rate (5/9) was similar in the control group. In conclusion, synchronization with CIDR-B was effective; however, the protocol may be improved by shortening the interval of CIDR placement to < or = 7 days and by reducing the circulating concentrations of progesterone to physiologic concentrations (< 4 ng/mL).
McCorkell
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Department of Veterinary Biomedical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, 52 Campus Drive, Saskatoon, Saskatchewan S7N 5B4, Canada. robert.mccorkell@sask.usask.ca
Woodbury
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MR
Adams
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GP
D000818:Animals; D003670:Deer / Q000502:physiology*; D004973:Estrus Synchronization / Q000502:physiology*; D005260:Female; D007315:Insemination, Artificial / Q000662:veterinary; D008297:Male; D006080:Ovarian Follicle / Q000000981:diagnostic imaging / Q000502:physiology*; D010062:Ovulation Induction / Q000379:methods / Q000662:veterinary*; D011374:Progesterone / Q000097:blood; D014463:Ultrasonography
D011374:Progesterone