Superovulation in wood bison (Bison bison athabascae): Effects of progesterone, treatment protocol and gonadotropin preparations for the induction of ovulation.

Experiments were done to determine the ovarian response and embryo production following superstimulation of wood bison. In Experiment 1 (Anovulatory season), the efficacy of pLH vs. hCG for inducing ovulation was compared in wood bison superstimulated with a single dose of pFSH in 0.5% hyaluronan and the effect of exogenous progesterone (PRID) on superovulatory response and embryo quality was examined. In Experiment 2 (Ovulatory season), the efficacy of pLH vs. hCG for the induction of ovulation was compared in wood bison superstimulated with pFSH in a single intramuscular dose vs. a two-dose regimen 48 h apart (split dose) in 0.5% hyaluronan. In Experiment 1, the number of CL was greater (P < 0.05) in bison treated with hCG than pLH (6.6 ± 1.8 vs. 2.8 ± 0.8) and in those that were not given PRID (6.0 ± 1.5 vs. 2.7 ± 1.0). There was no effect of progesterone treatment on embryo quality. In Experiment 2, the number of CL was greater (P < 0.05) in bison treated with hCG than with pLH (6.3 ± 0.8 vs. 3.8 ± 1.2) and in bison superstimulated with split dose vs. single dose of FSH (7.1 ± 0.9 vs. 3.0 ± 0.8). The number of ova/embryos and freezable embryos did not differ among groups in either experiment. In conclusion, hCG induced a greater ovulatory response than pLH in both seasons. Two doses of FSH induced the greatest superovulatory response during the ovulatory season. Exogenous progesterone did not improve embryo quality during the anovulatory season.

Ovarian synchronisation in wood bison (Bison bison athabascae) during the anovulatory season.

Two experiments were performed in wood bison during the anovulatory season to establish an effective protocol for ovarian synchronisation. In an untreated control phase, bison cows (n=19) were examined daily to establish the interval to new follicular wave emergence (4.9±0.7 days) for the purposes of comparison with the experimental treatments. In Experiment 1, bison were treated by transvaginal ultrasound-guided follicular ablation (n=9) or with 2mg, i.m., 17ß-oestradiol (n=10). In Experiment 2, bison were treated by follicular ablation (n=9) or with 2mg, i.m., 17ß-oestradiol +100mg, i.m., progesterone (n=10). In Experiment 1, the interval to new wave emergence for control, follicular ablation and 17ß-oestradiol-treated groups was 4.9±0.7, 1.1±0.1 and 3.1±0.4 days, respectively (P<0.05). The degree of synchrony was 2.4±0.4, 0.2±0.1 and 0.8±0.2 days, respectively (P<0.05). In Experiment 2, the interval to new wave emergence for control, follicular ablation and 17ß-oestradiol + progesterone-treated groups was 4.9±0.7, 1.2±0.2 and 3.3±0.3 days, respectively (P<0.05), and the degree of synchrony was 2.4±0.4, 0.2±0.1, and 0.8±0.2 days, respectively (P<0.05). The degree of synchrony did not differ between ablation and hormone treatment groups in either experiment, but was greater in treatment groups than in the untreated control phase. Both follicular ablation and hormone treatment shortened and decreased the variability in the interval to follicular wave emergence in bison, but wave emergence occurred earlier after follicular ablation.

Ovarian superstimulation and oocyte collection in wood bison (Bison bison athabascae) during the ovulatory season.

The objective of the study was to establish an effective ovarian superstimulatory protocol and subsequently obtain oocytes from bison by transvaginal ultrasound-guided follicular aspiration. Two experiments involving 22 wood bison were done during the breeding season (September to December). In experiment 1, the bison were given a luteolytic dose of prostaglandin (Day 0) and underwent follicular ablation (Day 8) to induce ovarian synchrony. Synchronized bison were then assigned randomly to two groups (n = 11 per group) and given either 200 mg FSH diluted in saline sc, or 200 mg FSH diluted in a proprietary slow-release formulation (SRF) im on Days 9 and 11. Prostaglandin was given to both groups on Day 11 followed by 25 mg LH on Day 13. Oocytes were collected by transvaginal ultrasound-guided aspiration of follicles ≥5 mm on Day 14. In experiment 2, bison were synchronized as in experiment 1 and assigned randomly to one of two groups (n = 11 per group) and given either a single dose of 2500 IU eCG im on Day 9, or 200 mg FSH sc on Days 9 and 11. Prostaglandin was given to both groups on Day 11, and LH (25 mg) was given on Day 13. Oocyte collection was done as described in experiment 1. Cumulus-oocyte-complexes (COC) were classified according to morphologic characteristics. In experiment 1, more follicles ≥5 mm were detected on Day 14 in bison treated with FSH versus eCG (12.2 ± 1.73 vs. 5.8 ± 0.52; P < 0.05), and more COC were collected from FSH-treated animals (7.2 ± 1.41 vs. 3.4 ± 0.62; P < 0.05). In experiment 2, the FSH-saline and FSH-SRF groups had a similar number (mean value ± standard error of the mean) of follicles ≥5 mm on Day 14 (12.4 ± 1.49 vs. 13.8 ± 1.24, respectively) and a similar number of COC were collected (6.5 ± 1.13 vs. 6.3 ± 0.96, respectively). The proportion of COC collected per follicle aspirated and the percentage of compact, expanded, and denuded oocytes did not differ between groups in either experiment 1 or 2. In summary, a two-dose regimen of FSH diluted in saline and given sc or in a SRF and given im induced a similar ovarian response in wood bison, whereas a single dose of eCG resulted in a significantly lower ovarian response. Overall, COC were collected from 55% of follicles after transvaginal, ultrasound-guided needle aspiration in wood bison.

Superovulation and embryo transfer in wood bison (Bison bison athabascae).

Two experiments were done to develop an effective superovulatory treatment protocol in wood bison for the purpose of embryo collection and transfer. In experiment 1, donor bison were assigned randomly to four treatment groups (N = 5 per group) to examine the effects of method of synchronization (follicular ablation vs. estradiol-progesterone treatment) and ovarian follicular superstimulation (single slow-release vs. split dose of FSH). Recipient bison were synchronized with donor bison by either follicular ablation (N = 8) or estradiol-progesterone treatment (N = 9). In experiment 2, bison were assigned randomly to four treatment groups (N = 5 per group) to examine the ovarian response to two versus four doses of FSH, and the effect of progesterone (ovarian superstimulation with or without an intravaginal progesterone-releasing device). Donor bison were inseminated with fresh chilled wood bison semen 12 and 24 hours after treatment with GnRH (experiment 1) or LH (experiment 2). The ovarian response was assessed using ultrasonography. In experiment 1, the number of large follicles (≥ 7 mm) increased in response to both FSH treatments, but the diameter of the largest follicle detected 4 and 5 days after the start of ovarian superstimulation was greater in bison treated with a single dose of FSH than in those treated with two doses (P < 0.05). A total of 10 ova and/or embryos were collected. One blastocyst was transferred to each of five recipient bison resulting in the birth of two live wood bison calves. In experiment 2, two doses of FSH resulted in a greater number of large follicles (≥ 9 mm) on Days 4, 5, and 6 (P < 0.05) after beginning of superstimulation (Day 0), and more ovulations than four doses of FSH (11.2 ± 2.4 vs. 6.4 ± 0.8; P < 0.05). Embryo collection was performed on only five donors, and a total of 19 ova and/or embryos were recovered. In summary, fewer FSH treatments were as good or better than multiple treatments, consistent with the notion that minimizing handling stress improves the superovulatory response in bison. Follicular ablation and estradiol plus progesterone treatment were effective for inducing ovarian synchronization in embryo donor and recipient bison, and an intravaginal progesterone-releasing device during superstimulatory treatment did not influence the superovulatory response or embryo collection. Delaying ovulation-inducing treatment (GnRH or LH) to 5 days after superstimulatory treatment resulted in a greater number of ovulations and improved embryo collection efficiency (experiment 2). Embryo collection and transfer resulted in live offspring from wild wood bison.

Serial ovarian ultrasonography in wild-caught wood bison (Bison bison athabascae).

The objectives of this study were to determine the feasibility of daily examination of wild-caught wood bison and to characterize the ovarian function using serial transrectal ultrasonography and blood hormone analysis. Ten 2-year-old wood bison heifers obtained from Elk Island National Park were placed in a corral adjacent to a handling system designed for restraining bison. The handling system was left open to the corral allowing the bison to explore it freely for 2 months. Active acclimation followed for a 2-week period, during which the bison were herded daily through the handling system and rewarded with whole oats. Finally, the bison were restrained in the handling system and rewarded with whole oats upon release. Once conditioned, daily transrectal examination of the ovaries was completed in 100% of attempts for 30 days (January-February) using a B-mode scanner with a 5 to 10-MHz linear array. Follicle size and numbers were recorded, and individual follicles were identified serially. Blood samples were collected daily and the serum was analyzed for FSH concentrations. Nonrandom changes were detected in the number of follicles ≥ 4 mm in diameter per day (P < 0.05). Each peak in follicle numbers was associated with the development of a single dominant follicle. The interval between the emergence of successive dominant follicles was 6.8 ± 0.6 days (mean ± SEM). The maximum diameter of the dominant follicle was 9.9 ± 0.4 mm. In conclusion, wild-caught wood bison were amenable to daily examination and blood sampling, and ovarian dynamics were characterized by wave-like development of anovulatory antral follicles. The demonstrated success of this approach to the study of ovarian function will be useful for characterizing the annual reproductive pattern in wood bison, which is necessary for the development of bison-specific protocols for controlling ovarian function for species conservation.

Superstimulatory response and oocyte collection in North American bison during the non-breeding season.

A 2×2 design was used to compare the ovarian response and oocyte collection characteristics in bison given a superstimulatory dose of eCG or FSH, with or without a follow-up dose of LH. Follicular wave emergence was synchronized by follicle ablation (Day -1) and bison were assigned randomly to two superstimulatory treatment groups (n=10 per group): (i) a single intramuscular dose of 2500IU of eCG given on Day 0, or (ii) two subcutaneous doses of 200mg of FSH given on Days 0 and 2. On Day 4, 200mg of LH was given intramuscularly in 5 bison in each superstimulatory treatment group. The study was done in two replicates (n=20 per replicate) involving a crossover design so that each animal was given the opposite superstimulatory treatment (eCG or FSH) during successive replicates. Cumulus-oocyte complexes (COC) were collected by transvaginal ultrasound-guided follicle aspiration, and were classified according to morphologic attributes as compact, expanded, or denuded. Superstimulatory treatment with FSH (vs. eCG) resulted in the development of more follicles ≥5mm (14.2±1.41 vs. 8.2±0.67; P<0.05; mean±SEM), and more follicles aspirated (12.4±1.3 vs. 6.3±0.6; P<0.04). Follow-up treatment with LH (vs. no LH) resulted in a greater proportion of expanded COC (37% vs. 15%; P<0.05), and a tendency for a higher COC collection rate (61% vs. 54%; P=0.08). In summary, superstimulation with FSH (vs. eCG) resulted in twice as many follicles available for aspiration and nearly twice as many COC collected in bison during the anovulatory season, and follow-up treatment with LH increased the proportion of expanded COC collected.

Superovulation in waptiti (Cervus elaphus) during the anovulatory season.

The objective was to evaluate the efficacy of three previously unreported ovarian superovulatory treatment protocols in wapiti. Protocols were initiated specifically at the time of ovarian follicular wave emergence, and intended to enable determination of the effects of frequency of treatment (i.e., animal handling) and LH supplementation on ovarian response. Thirteen parous wapiti hinds, 2 to 4 y of age, were used late in the anovulatory season (July). The ovaries were examined daily by transrectal ultrasonography. Hinds were given 5 mg estradiol 17-ß im (day of treatment designated as Day 0) to induce a new wave of ovarian follicular development. On the expected day of wave emergence (Day 3), hinds were assigned randomly to three treatment groups and given: (1) 100 mg FSH im once a day for 4 days (N = 5); (2) 200 mg FSH sc on Day 3 and Day 5 (N = 4); or (3) 200 mg FSH plus 2.5 mg LH sc on Day 3 and Day 5 (N = 4). All hinds were given 10 mg LH im on Day 6 to induce ovulation. The mean (± SEM) number of ovulations per animal in the respective groups was 6.2 ± 2.0, 15.5 ± 5.9, and 14.8 ± 2.7. In conclusion, the technique of inducing follicular wave emergence to initiate superovulatory treatment at the time of wave emergence was effective in wapiti during the anovulatory season. The most efficient and effective method of ovarian superovulation in this study involved administration of estradiol 17-ß on Day 0, followed by 200 mg FSH sc on Days 3 and 5, and induction of ovulation (10 mg of LH) on the evening of Day 6. Compared with conventional methods that require 14 days and handling the hinds six times, the protocol used herein reduced the treatment period to 8 days and the number of animal handlings to four.

Use of azaperone and zuclopenthixol acetate to facilitate translocation of white-tailed deer (Odocoileus virginianus).

Thirteen wild-caught white-tailed deer (Odocoileus virginianus) from two different holding sites were chemically immobilized to facilitate capture, processing, and translocation to a new facility. The deer were divided into two treatment groups on the basis of age and received i.m. injections of the immobilizing agents via remote drug delivery systems. Group 1 (<1 yr old; n = 6) animals were immobilized with a combination of xylazine 1 mg/kg i.m. and azaperone 0.3 mg/kg i.m. At the end of the procedure the deer received zuclopenthixol acetate 1 mg/kg i.m. and (to antagonize the xylazine) tolazoline 2 mg/kg i.m. Group 2 (>1 yr old; n = 7) deer were administered xylazine 1 mg/kg i.m.. tiletamine-zolazepam 1 mg/kg i.m., and ketamine 1 mg/kg i.m. The deer in this group received a combination of azaperone 0.3 mg/kg i.m. and zuclopenthixol acetate 1 mg/kg i.m. before reversal with tolazoline 2 mg/kg i.m. All deer were recovered in a trailer before being moved in small groups to the new facility and released into the new enclosures. Azaperone and zuclopenthixol acetate provided short- and long-term relief from anxiety and allowed the animals to gradually become familiar with their new surroundings without excitement, injuries, or mortalities. Two deer exhibited mild signs of extrapyramidal side effects, which suggests that they may have received a relative overdose of the tranquilizers.