Induction of ovarian follicular wave emergence in wapiti ( Cervus elaphus)

Abstract

Two experiments were done to test the effects of treatments designed to electively induce ovarian follicular wave emergence in wapiti for the purpose of group synchronization. In Experiment 1, hinds were assigned randomly to three groups and given saline im (controls; n = 5), 5 mg of estadiol-17ß im ( n = 4), or 5 mg estradiol-17ß plus 100 mg progesterone im ( n = 5). In Experiment 2, hinds were assigned randomly to two groups and given no treatment (controls; n = 6), or transvaginal ultrasound-guided follicle ablation ( n = 7). In both experiments, ovarian follicular dynamics were monitored by daily transrectal ultrasonography from Day 0 (day of treatment) to Day 9. In Experiment 1, blood samples were collected at each examination for measurement of serum concentrations of progesterone and FSH. Both experiments were conducted during the late anestrous period (July and August). The mean (±S.E.M.) day of wave emergence did not differ between the control and estradiol alone groups, but tended to be later in the estradiol plus progesterone group Day 4.0 ± 0.7, Day 3.5 ± 0.3, and Day 5.2 ± 0.2, respectively; P = 0.06). The interval from treatment to wave emergence was less variable in the estradiol plus progesterone group ( P < 0.05) and tended to be less variable in the estradiol-alone group ( P = 0.07) than in the control group. The day of wave emergence was more variable ( P < 0.05) and tended to be later ( P = 0.10) in the control group compared to the ablation group (Day 2.5 ± 0.8 versus Day 1.4 ± 0.2). All three treatments were effective in synchronizing ovarian follicular wave emergence among a group of wapiti hinds. Follicle ablation may be an alternative method for synchronization of follicular waves in estrus synchronization and superstimulatory protocols.