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A review of the scientific literature on bison was carried out as part of the National Farm Animal Care Council´s (NFACC) process of updating Canada’s current Code of Practice for the Care and Handling of Farmed Bison. Four priority welfare issues were identified: the effect of seasonality on the nutritional requirements of bison; bison behaviour; euthanasia on-farm; and pain. Bison reduce their feed intake and activity during winter, sparing energy reserves during periods of cold temperatures and food scarcity. To promote consistent carcass quality in this highly seasonal animal, producers commonly feed bison high grain diets. It has been suggested that feeding bison high concentrate finishing diets, greater than 80%, over a significant period of time, is likely to cause ruminal acidosis. Research is required into strategies that could help producers manage the effects of seasonality and to make it work to their advantage. When bison are unable to compensate for nutritional seasonality in summer it can lead to reduced herd fertility from poor nutrition and reduced body condition. Regarding behaviour, the handling of bison differs from traditional cattle handling techniques, as they do not move the same way through handling facilities. Injuries and death during handling are more likely to occur if bison are handled incorrectly. They are more excitable than cattle, which have been bred for calm temperaments. Bison have a very intact social structure that has definite spacing requirements. The flight zone of bison tends to be much greater than that of cattle, and bison can be moved most effectively if the handlers work on the edge of it. Bison that become severely stressed during handling can suffer from a recognized condition known as capture myopathy. Handling facilities should restrict bison’s vision and minimize loud noises. Bison should never be left in isolation as solitary bison display high levels of agitation. In the event of euthanizing bison on-farm, specific information regarding the gauge, calibre of firearm, and bullet selection is lacking. However, the combination of firearm and ammunition selected must achieve a muzzle energy of at least 1000 ft-lb (1356 J) for animals larger than 400lbs (181 kg). Understanding the correct landmarks for euthanizing bison are especially important as they are anatomically different from cattle. Due to the physical thickness of a bison skull, higher calibre firearms or heavier gauge shotguns are required than those used for other species. Bison producers in Canada rarely, castrate or brand animals, and they are seldom dehorned. There is currently a lack of peer reviewed research regarding the effect of painful procedures in bison, however, there is little reason to suspect their physiological responses to pain are different to cattle. Both freeze branding and hot-iron branding cause pain and distress in bison, however in cattle, freeze branding causes less acute pain at the time of the procedure which would likely be similar to bison.

The viruses circulating among Antarctic wildlife remain largely unknown. In an effort to identify viruses associated with Weddell seals (Leptonychotes weddellii) inhabiting the Ross Sea, vaginal and nasal swabs, and faecal samples were collected between November 2014 and February 2015. In addition, a Weddell seal kidney and South Polar skua (Stercorarius maccormicki) faeces were opportunistically sampled. Using high throughput sequencing, we identified and recovered 152 anellovirus genomes that share 63–70% genome-wide identities with other pinniped anelloviruses. Genome-wide pairwise comparisons coupled with phylogenetic analysis revealed two novel anellovirus species, tentatively named torque teno Leptonychotes weddellii virus (TTLwV) -1 and -2. TTLwV-1 (n = 133, genomes encompassing 40 genotypes) is highly recombinant, whereas TTLwV-2 (n = 19, genomes encompassing three genotypes) is relatively less recombinant. This study documents ubiquitous TTLwVs among Weddell seals in Antarctica with frequent co-infection by multiple genotypes, however, the role these anelloviruses play in seal health remains unknown.

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.

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 (P0.05). 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 (P0.05) after beginning of superstimulation (Day 0), and more ovulations than four doses of FSH (11.2 ± 2.4 vs. 6.4 ± 0.8; P0.05). 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.

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.

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; P0.05; mean±SEM), and more follicles aspirated (12.4±1.3 vs. 6.3±0.6; P0.04). Follow-up treatment with LH (vs. no LH) resulted in a greater proportion of expanded COC (37% vs. 15%; P0.05), 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.

Handling North American bison can pose risk to the handler and evoke stress in the animal. Moreover, this induced stress might affect qualities of semen collected by electroejaculation. The objective of this study was to investigate if a long acting neuroleptic tranquilizer (LAN) would reduce the stress of bison and thereby improve the quality of electroejaculated semen. Eight experimental replicates were conducted between May and November. In each replicate, the same six bison bulls were randomly assigned into LAN-treated (n=3) and non-treated control (n=3) groups. Pipothiazine palmitate (Piportil L4) was administered intramuscularly as a single dose of 100 mg in replicates 1-4 or 200 mg in replicates 5-8. Within each replicate, semen was collected by electroejaculation at 4, 6, 11 and 13 days post treatment. Behavioral parameters, sperm morphology and motility parameters were analyzed. A blood sample was collected before each electroejaculation and serum concentrations of testosterone, cortisol and corticosterone were determined. Treatment bulls with 100 mg of Piportil L4 reduced the restraint time and the struggling of bison bulls during handling compared to the control group (P0.05). Semen motility parameters and serum concentrations of testosterone, cortisol and corticosterone were not significantly affected when 100mg of the LAN was administered (P0.05). However, giving 200 mg of Piportil L4 reduced the restraint time of bison bulls and the duration of semen collection (P0.05). Also, this treatment improved total and progressive sperm motilities when compared to the respective controls (P0.05). Interestingly, serum concentration of corticosterone, as an endocrine stress indicator, was decreased after administration of 200mg of Pipothiazine palmitate, while testosterone concentrations were increased compared to those values in untreated control bulls (corticosterone: 0.10±0.01 compared with 0.15±0.02 ng/mL; testosterone: 9.11±1.68 compared with 5.33±0.74 ng/mL; P0.05). In conclusion, this study demonstrated that a treatment dose of 200mg of Piportil L4 can decrease the behavioral and endocrine stress responses in bison bulls, which indirectly increasing testosterone concentrations and improving semen quality.

Brucellosis and tuberculosis are endemic in Wood Buffalo National Park, the largest reserve of wood bison (Bison bison athabascae) in Canada. Our goal is to produce and preserve disease-free embryos for the purpose of wood bison repopulation. This study was designed to determine if embryo collection is feasible in wood bison during the anovulatory season (May–July) and to test if progesterone priming is required for superovulation. A 2-by-2 design was used to determine the effectiveness of LH (Lutropin) or hCG (Chorulon) for induction of ovulation with or without intravaginal progesterone releasing device (PRID) in 32 wood bison cows. Follicular wave emergence was synchronized among bison by transvaginal ultrasound-guided follicle ablation. Synchronized bison were assigned to 4 groups: PRID+LH (n = 12), PRID+hCG (n = 4), no-PRID+LH (n = 12) and no-PRID+hCG (n = 4). A PRID was inserted on the day of follicular ablation in the respective groups. A single SC dose of 400 mg FSH (Folltropin) in a slow-release formulation was given the day after follicular ablation (i.e. on the expected day of a new follicular wave emergence, Day 0). The PRID was removed on Day 4 and either 25 mg LH or 2000 IU hCG was given IM on Day 5. Artificial insemination was done at 24, 36 and 48 h after LH or hCG treatment. Embryos were collected nonsurgically on Day 13 using commercial bovine equipment. Transrectal ultrasonography was done on Days 0, 5, 6, 7, 8 and 13 to record follicular and ovulatory responses. Count data (mean ± SEM) were analysed by two-way ANOVA and proportions by chi square. The number of ovulatory-sized follicles (≥10 mm) on Day 5 did not differ among groups (P = 0.33; Table 1). Ovulation rate (number of ovulations/number of follicles ≥10 mm) was greater in bison treated with hCG (P

Handling induces stress in North American bison that can lead to injuries for both handlers and animals. Moreover, this induced stress may result in variations in collection and quality of the semen. The objective of this study was to investigate if a long-acting neuroleptic (LAN) can lower the stress on bison bulls, allowing for safer handling and improvement in the quantity and quality of the collected semen. For this study, 6 mature bison bulls (3 Bison bison bison and 3 Bison bison athabascae) housed at the Native Hoofstock Centre, near Saskatoon, SK, Canada, were used. For each trial, bison bulls were randomly separated into 2 groups: LAN-treated (n = 3) and nontreated control (n = 3). In the treatment group, each bull was injected with 100 mg of Piportil L4® (piperodine phenothiazine, a LAN with antipsychotic properties and weak sedative activity that has a prolonged duration of action ≈2 wk). After injection, both groups were given a 5-day rest period before semen collection. All bison were collected by electroejaculation, twice a week for 2 wk with a minimum 48 h of rest between collections (total of 3 trials; 4 collections per trial). Between each trial, a rest period of 1 wk was given to the bulls. To evaluate the stress level of the animal, the bull’s heart and respiration rates were recorded before and after each collection. Electroejaculated semen was kept at 37°C and transported to the laboratory for further semen analysis (≈2 h). Semen was analysed using computer assisted sperm analyzer. Several parameters including volume, concentration, total motility, progressive motility, velocity curvilinear (VCL), velocity average path (VAP), and velocity straight line (VSL) were recorded. The data were analysed using two-way ANOVA (SAS 9.2; SAS Institute, inc., Cary, NC, USA). Data are presented as mean ± SD and P

Reclamation of Canada’s threatened wood bison (Bison bison athabascae) herd is complicated by endemic disease. As part of an overall goal to conserve bison genetics, the specific objective of this study was to develop a protocol to control follicular wave emergence in bison for the purposes of ovarian superstimulation and collection of disease-free oocytes. In an initial study, the synchronizing effect of follicular ablation and estradiol (E2) treatment was examined. Ablation was effective, but the effects of E2 (5 mg) were confounded by treatment-induced ovulation in some animals. Two experiments were done to determine the effect of a reduced dose of E2 or the addition of progesterone (P4) in comparison with follicular ablation. Bison cows (n = 19), ≥3 years old, were scanned for 14 days to determine the mean and variance in the interval to follicular wave emergence (control phase). In Experiment 1, bison were assigned randomly to 2 groups: follicular ablation (n = 9) or 2 mg of E2i.m. (n = 10). In Experiment 2, the same bison were randomly assigned to 2 groups: follicular ablation (n = 9) or 2 mg of E2+ 100 mg of P4 i.m. (n = 10). Ablation involved transvaginal ultrasound-guided aspiration of all follicles ≥5 mm. Wave emergence was determined retrospectively by identification of the follicle destined to become dominant at an initial diameter of 4 to 5 mm, with a concurrent increase in the number of follicles ≥4 mm. The interval and variation in the interval to emergence of a new follicular wave was compared among the control phase and treatment groups by ANOVA. In Experiment 1, the interval to new wave emergence (mean ± SEM) was 4.9 ± 0.66, 1.1 ± 0.11, and 2.4 ± 0.47 days from the start of the control phase, follicular ablation, and E2 treatment, respectively (P < 0.001). The degree of synchrony (residuals) was 2.4 ± 0.36, 0.2 ± 0.09, and 1.2 ± 0.24 days for the control phase, follicular ablation, and E2 treatment, respectively (P < 0.001). Ovulation was detected in 1 bison treated with E2. In Experiment 2, the interval to new wave emergence (mean ± SEM) was 4.9 ± 0.66, 1.2 ± 0.15, and 2.9 ± 0.31 days from the start of the control phase, follicular ablation, and E2 + P4 treatment, respectively (P < 0.001). The degree of synchrony was 2.4 ± 0.36, 0.2 ± 0.08, and 0.7 ± 0.20 days for the control phase, follicular ablation, and E2 + P4 treatment, respectively (P < 0.001), and no ovulations were detected. In conclusion, follicular ablation, E2, and E2 + P4 treatments all shortened and decreased the variability in the interval to new wave emergence in bison, but follicular ablation consistently produced a quicker and more synchronous response. Supported by grants from the Advancing Canadian Agriculture and Agri-Food Fund (ACAAF), the Agri-Food Innovation Fund, Parks Canada, the World Wildlife Fund, and the Northwest Territories.

Two methods for synchronizing ovarian follicular development in both wood bison (Bison bison athabascae) and plains bison (Bison bison bison) were tested as part of a project to conserve wood bison through the application of advanced reproductive technologies. A secondary objective was to test the effect of a long-acting neurolept tranquilizer, pipothiazine palmitate, on ovarian function in bison. Female wood bison (4 years old; n = 14) and plains bison (2-8 years old, n = 10), previously conditioned to daily examination in a chute, were divided randomly into 3 groups in which 1) ovarian follicles ≥5 mm were ablated by ultrasound-guided transvaginal follicle aspiration, 2) 5 mg of estradiol-17β in canola oil was given i.m. or 3) no treatment was given (control). The experiment was conducted in 3 replicates so that each animal rotated through each of the groups. Half of the bison, blocked by subspecies and treatment group, were given a single dose (150 mg) of pipothiazine palmitate i.m. The ovaries were examined daily by transrectal ultrasonography beginning 4 days before treatment and continuing until the dominant follicle of a new wave reached a diameter of 10 mm. No effect of treatment with pipothiazine palmitate was detected for any end point. In addition, no differences were detected between wood and plains bison for any end point. Consequently the pipothiazine palmitate and subspecies treatment groups were collapsed for further analyses. The interval and variation in the interval to new follicular wave emergence were compared by ANOVA. Wave emergence was detected on Day 1.0 ± 0.2 (mean ± SEM; Day 0 = day of treatment) in the follicle ablation group, and was earlier (P < 0.05) than in both the estradiol (Day 3.3 ± 0.3) and control (Day 4.0 ± 0.4) groups. The interval to follicle wave emergence was least variable in the follicle ablation group (P < 0.05) and tended to be less variable in the estradiol group (P = 0.09) than in the control group (residuals, 0.1 ± 0.04, 1.0 ± 0.2, and 1.6 ± 0.3 days, respectively). Ovulations occurred subsequent to estradiol administration in 10 of 23 (43%) bison. In conclusion, ovarian follicular wave emergence can be synchronized in bison during the anovulatory season. Follicular ablation consistently shortened and decreased the variability in the interval to new wave emergence. The synchronizing effect of estradiol was confounded by the induction of ovulation. Progesterone will be added in future studies to control the ovulatory effect of estradiol. Pipothiazine palmitate had no discernable effect on ovarian function and maybe useful in reducing the effects of handling stress on untrained animals. Supported by a grants from the Advancing Canadian Agriculture and Agri-Food Fund, the Agri-Food Innovation Fund, Parks Canada, the World Wildlife Fund, and the Northwest Territories.

Endemic tuberculosis and brucellosis threaten Canada’s wood bison population. For the purposes of developing a procedure to harvest pathogen-free sperm from bison, a sperm separation and purification product, BoviPure, was tested to determine its effect on bison sperm viability before and after cryopreservation. BoviPure (NidaCon International AB, Mölndal, Sweden) is a density centrifugation gradient system that contains trypsin and is designed to separate motile from non-motile sperm and remove infectious pathogens. Spermatozoa were expelled from the caudal epididymis of bison testicles collected at slaughter and diluted in 3 to 5 mL of TCM-199 medium (Gibco, Burlington, Ontario, Canada). After 1 h of incubation at 37°C, 1 to 1.5 mL of diluted sample (approximately 300 × 106 sperm) was placed in (1) a BoviPure gradient containing trypsin (n = 18 samples), (2) a BoviPure gradient without trypsin (n = 10 samples), or 3) left untreated (control; n = 20). Gradients were centrifuged at 300g for 20 min. The sperm pellet was resuspended in 5 mL of TCM-199 medium and recentrifuged at 500 g for 10 min. Total and progressive motility were estimated using computer-assisted sperm analysis (CASA). Gradient-treated and untreated sperm samples were diluted in an egg yolk extender (Triladyl; Minitube Canada, Ingersoll, Ontario, Canada), placed in 0.5-mL straws (50-200 × 106 spermatozoa per straw), frozen, and stored in liquid nitrogen for a minimum of 24 h. Semen straws were thawed by plunging in a 37°C water bath for 30 s, and motility measurements were taken immediately by CASA. Total and progressive motility were compared among groups by analysis of variance. Before cryopreservation, total motility and progressive motility were not affected by gradient processing. Total motility was 85±5.1%, 80±4.8%, and 77 ± 3.7% for untreated, BoviPure with trypsin, and BoviPure without trypsin, respectively (mean ± SEM), and progressive motility was 74 ± 2.7%, 77 ± 3.8%, and 68 ± 4.7%, respectively. After freezing and thawing, total motility decreased compared to unfrozen samples (P < 0.0001) but was not different among groups (37 ± 3.6%, 33 ± 3.7%, and 29 ± 4.8% for untreated, BoviPure with trypsin, and BoviPure without trypsin, respectively). Similarly, progressive motility decreased compared to unfrozen samples (P < 0.0001) but was not different among groups (26 ± 3.6%, 21 ± 3.7%, and 14.5 ± 4.9% for untreated, BoviPure with trypsin, and BoviPure without trypsin, respectively). We conclude that the BoviPure gradient with or without trypsin does not influence total motility or progressive motility of bison sperm either before or after cryopreservation and has potential as a method of harvesting pathogen-free sperm from wild animals of unknown disease status. This study was supported by Canadian Adaptation and Rural Development in Saskatchewan.

As part of a project involving reproductive biotechnology as a method of preserving Canada’s threatened wood bison population, an experiment was designed to test the effectiveness of steroid-induced ovarian synchronization and fixed-timed AI. The experiment was performed in the early ovulatory season (September) with female wood bison (4 years old, n = 13) and plains bison (2 years old, n = 4, and 8 years old, n = 3). Based on results of a preceding study, progesterone was combined with estradiol as a synchronization treatment to mitigate against untimely ovulation. The bison were blocked by subspecies and assigned randomly to a control group (no treatment; n = 10) or given estradiol 17β (2.5 mg) + progesterone (50 mg) in canola oil i.m. and a progesterone-releasing intravaginal device (Cue-mate™, Bioniche, Belleville, Ontario, Canada) on Day 0 (n = 10). On Day 8, the Cue-mate™ device was removed and PGF (500 mg Estrumate®, Mallinckrodt Vet GmbH, Friesoythe, Germany) was given to induce luteolysis. On Day 10, all bison were given 5 mg of LH (Lutropin®-V, Bioniche) and artificially inseminated 12 h later with semen collected and frozen previously from wood bison of the same herd. The ovaries were examined daily by transrectal ultrasonography beginning 5 days before treatment and thereafter until the first post-treatment ovulation. Ultrasonographic pregnancy diagnosis was done 30 days post-insemination. No differences were detected between wood and plains bison for any end point, and data were combined for further statistical analyses. Ovarian follicular wave emergence occurred on Day 4.1 ± 0.8 (mean ± SEM) and 4.1 ± 0.3 in the control and treatment groups, respectively (P = 99.3). The interval to new wave emergence was less variable in bison treated with estradiol + progesterone than in untreated controls (residuals, 0.7 ± 0.2 and 1.9 ± 0.5 days, respectively; P < 0.05). The interval from LH administration to ovulation was 2.7 ± 0.6 and 5.4 ± 1.9 days for the treatment and control groups, respectively, and was less variable in the treatment group than in controls (residuals, 1.2 ± 0.4 and 5.3 ± 0.8 days, respectively; P < 0.05). The diameter of the preovulatory follicle was not different between groups and was, on average, 15.2 ± 1.1 mm. Pregnancy was diagnosed in 3 bison in the treatment group and 2 in the control group. In conclusion, treatment with estradiol and progesterone effectively synchronized the interval to wave emergence, and subsequent LH treatment resulted in a synchronous ovulatory response necessary for fixed-time AI in bison. Although the pregnancy rate was modest, perhaps because of issues with semen quality, timing of AI, or quality of the ovulated oocyte, this represents the first report of pregnancy in bison from fixed-time insemination. Supported by grants from the Advancing Canadian Agriculture and Agri-Food Fund, the Agri-Food Innovation Fund, Parks Canada, the World Wildlife Fund, and the Northwest Territories.

In Canada, brucellosis and tuberculosis threaten an estimated 4500 wood bison (Bison bison athabascae), a species considered at risk by the Committee on the Status of Endangered Wildlife In Canada (COSEWIC). To help rescue this species, our Wood Bison Reproductive Research group proposes to employ advanced reproductive technologies. Unfortunately, little is known about the reproductive physiology of the wood bison, which hinders the application of these reproductive technologies. In order to modify advanced reproductive techniques developed in cattle for use in wood bison, the large amounts of semen, embryos, and oocytes from wood bison required are not available. The purpose of this study was to compare semen collected from the more abundant and closely related plains bison (Bison bison bison) with that of wood bison. Semen from 3 wood and 4 plains bison were collected by electro-ejaculation during the summer of 2007. Andrological parameters of morphology and motility were recorded on fresh semen, extended semen, and post-thawed semen samples. A Student's t-test was used to compare the results of these two groups. Semen was cryopreserved using two commercially available cryopreservation media (Andromed and Triladyl, Minitube Canada, Ingersoll, Ontario, Canada). Sperm morphology and motility were not different between electro-ejaculated samples from plains and wood bison (P > 0.05). Also, no difference was found in the survival rate of sperm from the electro-ejaculated samples between plains and wood bison after freezing and then thawing using an egg-yolk based extender (Triladyl) or an extender containing no products of animal origin (Andromed). A difference between cryopreservation media was found; post-thaw motility of Triladyl-treated sperm was higher (29%) than that of the Andromed-treated sperm (12%). Due to lack of previous success with preserving electro-ejaculated semen in media free of animal-origin products, motility assays were performed to evaluate if spermatozoa retrieved from epididymides of plains bison can be cryopreserved in Andromed. Interestingly, cyropreserved epididymal spermatozoa had a higher motility than cryopreserved electro-ejaculated sperm after freezing-thawing procedures using a medium containing no products of source animal (respectively, 30% v. 7%). This result suggests that there may be a factor secreted by the reproductive accessory glands that interferes with the post-thaw survivability of bison sperm. In conclusion, this study supports the hypothesis that semen from plains bison behaves similarly to that of wood bison semen during cryopreservation and therefore could be used to establish protocols for advanced reproductive technologies in wood bison. This project was supported by Canadian Adaptation and Rural Development in Saskatchewan.

Wapiti are seasonally polyestrous. The transition into and out of the breeding season is marked by resumption of ovulation in autumn and cessation of ovulation in winter. Onset of ovulatory cyclicity is distinct and associated with aggressive breeding behavior of stags in rut. Cessation of ovulation at the end of the breeding season is not distinguished by behavioral patterns. The objective of the present study was to characterize follicular and luteal dynamics in wapiti during the transitional periods into and out of the breeding seasons. Transition from anestrus to estrus was monitored in 15 hinds, aged 2 to 14 years, over two successive seasons (11 in year 1, with 5 hinds from year 1 used again in year 2 along with 4 new hinds; n = 20 observations). Transition from estrus to anestrus was monitored in 11 hinds over 1 season (n = 11 observations). Hinds were maintained on a farm near Saskatoon, Saskatchewan (52°07′N, 106°38′W). The ovaries were examined daily during September through October by transrectral ultrasonography using a B-mode ultrasound machine and a 7.5 MHz linear array transducer for transition to estrus, and December through April for transition to anestrus. The first ovulation was recorded on September 15 and all hinds had ovulated for the first time by October 7. In 17 of 20 observations, the duration of the first interovulatory interval (IOI) was 9.3 ± 0.4 days (mean ± SEM). With one exception, these IOIs were characterized by one wave of follicular development. The remaining three IOIs ranged from 16 to 23 days and consisted of two or three waves of follicle development. The second ovulation occurred by October 15 in hinds with a short IOI and by October 17 in all remaining hinds. The mean dates of first and last ovulation were September 25 and February 7, respectively, an interval of 135 days. The median date of the last ovulation was February 15 and the range was from December 3 to March 22. Duration of the last IOI of the season (21.2 ± 0.6 days) was similar to the notional 21-day cycle for wapiti, but longer (P < 0.05) than the duration of the first IOI (10.9 ± 1.0 days). Maximum diameters of the first 2 ovulatory follicles were similar (11.3 ± 0.4 vs. 11.3 ± 0.2 mm), but were larger (P < 0.05) than the last 2 ovulatory follicles of the breeding season (10.3 ± 0.3 vs. 10.1 ± 0.4 mm). Maximum diameter of the corpus luteum (CL) tended (P = 0.06) to be smaller for the short IOI than for longer IOI of the first and last cycles. Diameter of the last CL of the season was not different from that of the previous CL (12.8 ± 0.6 vs. 12.5 ± 0.6 mm); however, it was detected for a longer period (22.3 ± 1.2 vs. 19.3 ± 0.7 days; P < 0.05). Estrous cycles during transition into the breeding season have been described as being irregular and those out of the breeding season as increasingly long. In the present study, the transition periods were characterized by regular events. Transition to regular estrous cycles was preceded by one short (9 days) IOI. The last IOI of the breeding season was the same as that reported during the rut. Transition to anestrus occurred most commonly in February and was marked by a failure of the dominant follicle to ovulate after luteal regression.