Evaluation of an ovarian synchronization scheme for fixed-time artificial insemination in wapiti

The effect of equine chorionic gonadotropin (eCG) on pregnancy rates of white-tailed deer following fixed-timed artificial insemination

Control of the white-tailed doe's reproductive cycle is not well documented. The objective was to determine the effects of giving equine chorionic gonadotropin (eCG) at progesterone device removal on fixed time artificial insemination (FTAI) pregnancy rates in white-tailed does. All does (n = 74) were synchronized with a vaginal progesterone implant (CIDR; 0.3 g progesterone), inserted on Day 0 (without regard to stage of estrous cycle), removed 14 days later, and subjected to FTAI, on average, 60 h post-CIDR removal. Of these, 34 were given 200 IU (im) of eCG at CIDR removal. Overall, FTAI pregnancy rate was 50% across 2 yrs (effect of year, P = 0.35). Administration of eCG at CIDR removal did not affect (P = 0.16) pregnancy rate (eCG = 59%; no eCG = 43%). Pregnancy rates were not affected by vulva score or doe disposition. Does that were ≤ 4 yrs old were more likely (P = 0.01) to become pregnant than does > 4 yrs of age. Does inseminated ≥ 60.5 h after CIDR removal were 22 times more likely (P = 0.002) to become pregnant to FTAI than does inseminated < 60.5 h. When frozen-thawed semen was deposited in the cervix or uterus, does were 17 times more likely (P = 0.005) to become pregnant compared with those receiving intravaginal insemination. Fecundity was not different (P = 0.73) across treatment groups (1.6 ± 0.11; no eCG vs. 1.7 ± 0.10; eCG). Furthermore, fecundity of does pregnant to FTAI was not different (P = 0.72) compared with does pregnant to clean-up bucks (1.7 ± 0.08; AI does vs. 1.7 ± 0.09; clean-up bucks). In summary, white-tailed does were successfully inseminated using a 14 days FTAI protocol, eCG may not be essential for acceptable pregnancy rates, and increased pregnancy rates may result when FTAI is done ≥ 60.5 h after progesterone device removal.

Re-use of intravaginal progesterone devices associated with the Short-term Protocol for timed artificial insemination in goats

Because intravaginal devices impregnated with 0.3 g of progesterone (i.e., CIDR-G) contain remaining hormone after their use in a Short-term Protocol (5 to 7 d of treatment), the reuse of these devices is proposed in goats. Two experiments were designed to study the effects of the reutilization of CIDR-G, establishing serum progesterone concentrations, follicular development, ovulatory response, and fertility. Experiment 1: Thirty dairy goats received a Short-term Protocol for 5 d using CIDR-G of first use (new devices, n = 10), second use (previously used for 5 d, n = 10), or third use (previously used twice for 5 d each time, n = 10). Goats were given (im) prostaglandin F(2α) (10 mg dinoprost) and eCG (300 IU) at device insertion and withdrawal, respectively. Serum progesterone concentrations induced by CIDR-G of first use were higher than CIDR-G of second or third use (P < 0.05); concentrations were consistently > 1 ng/mL in all females treated with reused devices. Estrus and ovulation were synchronized in 100% of goats (no differences among treatments). All females treated with new devices, but only 80% of females treated with re-used devices ovulated a new follicle that emerged after CIDR-G insertion (P = NS). Ovulation occurred between 60 and 70 h after device removal (no differences among groups). Experiment 2: In goats subjected to a Short-term Protocol followed by AI at 54 h after CIDR-G, pregnancy rates with CIDR-G of first, second, and third use were 75.3% (64/85), 67.4% (60/89), and 62.1% (54/87), respectively (devices of first versus third use, P < 0.05). In summary, intravaginal devices originally containing 0.3 g of progesterone appeared effective to synchronize estrus and ovulation after first, second and third use in the Short-term Protocol. Although the pregnancy rate with reused devices was acceptable (i.e., > 60%), it was significantly lower than that achieved with new devices and further studies to ensure adequate follicular turnover are required.

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

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), 5mg of estadiol-17beta im (n=4), or 5mg estradiol-17beta plus 100mg 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.