Effects of the Immunocontraceptive Gonacon on Pregnancy in Brucella-Seropositive American bison (Bison bison).

The purpose of this study was to determine if the number of pregnancies in naturally infected Brucella abortus-positive bison (Bison bison) cows would be reduced over a period of 5 yr after one treatment with 3000 µg gonadotropin-releasing hormone immunocontraceptive (GonaCon) compared to a similar group of naturally infected B. abortus-positive bison cows not treated with GonaCon. In each of the 5 yr, GonaCon-treated cows produced fewer offspring in relation to number of cows than the nontreated cows. Fisher's Exact test comparing offspring produced during the first reproductive season showed a significant difference between the two groups (P=0.0028). Differences in number of calves produced in GonaCon-treated and control groups were also noted in remaining years, but statistics were not applied because of data constraints. These data indicate that one treatment with GonaCon in brucellosis-seropositive female bison reduced pregnancies over five reproductive years. Thus, immunocontraception could potentially be used to manage brucellosis in affected herds.

Immune Responses and Efficacy of Brucella Abortus Strain RB51 in Bison After Delivery in a Dry Dart Formulation or by Parenteral Inoculation.

Bison (Bison bison) heifer calves (n = 32) were randomly assigned to control or vaccination with 1010 colony-forming units of Brucella abortus strain RB51 (RB51) vaccine by single or boostered parenteral delivery, or by surgical implantation of a dry dart formulation (n = 8/trt). Serum and/or peripheral blood mononuclear cells (PBMC) were obtained at 0, 4, 8, 13, 16, 21, and 24 wks after initial vaccination and at 0, 4, 8, 12, 15, 22, and 27 wks after booster vaccination to characterize humoral and cellular immune responses to RB51. Bison in both RB51 vaccination treatments demonstrated greater (P < 0.0001) serum humoral responses when compared to non-vaccinates, with parenteral vaccinates demonstrating greater (P < 0.01) responses when compared to mean responses of bison inoculated with the dry dart. Only the booster vaccinated treatment demonstrated greater (P < 0.0001) humoral responses than control bison in samples collected after re-inoculation. At 4, 8, 12, 16, and 24 wks after initial vaccination, PBMC from parenteral RB51 vaccinates demonstrated greater proliferative responses to RB51 when compared to responses of control animals. In comparison, bison inoculated with the RB51 dry dart did not demonstrate greater (P > 0.05) proliferative responses when compared to responses of non-vaccinates. Bison were pasture bred and pregnant animals experimentally challenged in mid-gestation with 107 CFU of B. abortus strain 2,308. Bison in parenteral vaccination treatments had reduced (P < 0.05) abortions and infection in uterine and fetal samples as compared to non-vaccinated bison, with booster vaccinates tending to have the lowest colonization (CFU/gm) in tissues. In comparison, the dry dart formulation did reduce abortion (P < 0.05) but not infection (P > 0.05) in most tissues when compared to non-vaccinated bison. The results of this study reaffirm the efficacy of boostered parenteral vaccination of bison with RB51 in preventing brucellosis. Our data also suggests that the novel dry dart RB51 formulation does not induce sufficient efficacy in bison after a single inoculation.

Production of embryos and a live offspring using post mortem reproductive material from bison (Bison bison bison) originating in Yellowstone National Park, USA.

Bison from Yellowstone National Park (YNP) have an important genetic history. As one of the few wild herds of bison with no evidence of cattle DNA introgression and a large enough population to maintain genetic diversity, they are considered a conservation priority for the species. Unfortunately, there is a high prevalence of the zoonotic disease brucellosis in the herd. Part of the management strategy for controlling the disease and herd size in YNP is to remove bison from the population during the winter migration out of the park. This interagency management cull provides an opportunity to collect a large number of oocytes from a wild bison population for genetic banking and research purposes. During the winters of 2014-2018, which is the nonbreeding season for bison, oocytes were collected post mortem and used to determine the effects of donor reproductive maturity and pregnancy status on oocyte quality and in vitro fertilization (IVF) outcomes, and to demonstrate the feasibility of producing healthy offspring. Cumulus oocyte complexes (COCs) were placed into an in vitro embryo production (IVP) system, and on days 7, 7.5, and 8 of in vitro culture (Day 0 = day of in vitro fertilization) embryos were assessed for developmental stage and quality prior to vitrification. Embryos were then stored in liquid nitrogen until the breeding season when a subset were warmed, cultured for 6 h, evaluated for survival, and transferred to healthy bison recipients. There were no significant differences in the ability of recovered COCs to support blastocyst development based on female reproductive maturity or pregnancy status (juvenile 79/959 (8.2%) vs sexually mature 547/6544 (8.4%); non-pregnant 188/2302 (8.2%) vs pregnant 556/6122 (9.1%)). Following the transfer of 15 embryos to 10 recipients, one healthy female calf was born. This work demonstrates that live offspring can be generated from COCs collected from YNP bison post mortem in the non-breeding season, and that gamete recovery can be a valuable tool for conservation of valuable genetics for this species while mitigating diseases like brucellosis.

Tissue Residue Levels after Immobilization of Rocky Mountain Elk ( Cervus elaphus nelsoni) using a Combination of Nalbuphine, Medetomidine, and Azaperone Antagonized with Naltrexone, Atipamezole, and Tolazoline.

Previous studies demonstrated that nalbuphine, medetomidine, and azaperone (NalMed-A) can effectively immobilize adult elk ( Cervus elaphus nelsoni), and be antagonized using naltrexone and atipamezole, with or without tolazoline. To assess duration of tissue residues for this immobilization package, we immobilized 14 captive adult elk with NalMed-A, then euthanized animals and collected tissues 0, 3, 6, 14, 21, or 28 d later. Except for two animals euthanized immediately, all elk were recovered using naltrexone, atipamezole, and tolazoline. Tissue residues (≥0.01 parts per million) for the tranquilizers nalbuphine, medetomidine, and azaperone were detected in liver and muscle tissue samples from elk euthanized within 40 min postinjection (PI) and one animal that died 12-24 h PI, but not in tissues from any of the animals euthanized at 3, 6, 14, 21, or 28 d PI. Tissue residues for the antagonists naltrexone, atipamezole, and tolazoline were detected in liver and muscle of the animal that died 12-24 h PI. Only naltrexone was detected in liver from the two elk euthanized at day 3, and no antagonist residues were detected thereafter.

THE EFFICACY OF NALBUPHINE, MEDETOMIDINE, AND AZAPERONE IN IMMOBILIZING AMERICAN BISON (BISON BISON).

We evaluated a combination of nalbuphine, medetomidine, and azaperone (NalMed-A) in 12 American bison ( Bison bison ) during 13 sedation handling events. The mean (SE) dosage was 0.4 (0.02) mg/kg nalbuphine, 0.08 (0.003) mg/kg medetomidine, and 0.08 (0.003) mg/kg azaperone contained in an average delivery volume of 0.8 mL/100 kg. Two animals required a supplemental dose for safe handling (additive dose used in calculating means) and a third animal was not adequately sedated despite a supplemental dose. Bison immobilized with NalMed-A showed good sedation in 12 of 13 handling attempts. Advantages of this drug combination included a relatively low delivery volume, rapid antagonism, and minimal regulatory burden for component drugs. The most consistent disadvantage was hypoxemia, and oxygen supplementation is recommended when using this sedative combination in bison.

Vaccination of Elk (Cervus canadensis) with Brucella abortus Strain RB51 Overexpressing Superoxide Dismutase and Glycosyltransferase Genes Does Not Induce Adequate Protection against Experimental Brucella abortus Challenge.

In recent years, elk (Cervus canadensis) have been implicated as the source of Brucella abortus infection for numerous cattle herds in the Greater Yellowstone Area. In the face of environmental and ecological changes on the landscape, the range of infected elk is expanding. Consequently, the development of effective disease management strategies for wild elk herds is of utmost importance, not only for the prevention of reintroduction of brucellosis to cattle, but also for the overall health of the Greater Yellowstone Area elk populations. In two studies, we evaluated the efficacy of B. abortus strain RB51 over-expressing superoxide dismutase and glycosyltransferase for protecting elk from infection and disease caused by B. abortus after experimental infection with a virulent B. abortus strain. Our data indicate that the recombinant vaccine does not protect elk against brucellosis. Further, work is needed for development of an effective brucellosis vaccine for use in elk.