Determination of hematological and biochemical values blood parameters for European bison (Bison bonasus).

Hematological and biochemical blood parameters are important tools for evaluating animals' health. They might be crucial in assessing the health of entire populations of wild animals, such as European bison (Bison bonasus). The aim of this study was to establish hematological and biochemical values for healthy European bison and to determine whether there were significant relations with age and sex. Blood samples were collected from 79 animals and tested according to generally accepted standards and the results were subjected to statistical analysis. Most of the age and gender-related correlations found in our study were predictable based on previous reports. Due to bone growth, juvenile animals have typically higher ALP and P concentrations relative to adults. Several age-related dependencies were surprising, like higher Na concentration in younger European bison. Determination of hematological and biochemical blood parameters of healthy European bison may significantly contribute to the further restitution of this endangered species.

The behavior and welfare of neglected species: some examples from fish and mammals.

Animal welfare is the state of an animal's body and mind and the level to which its requirements are satisfied. Animal welfare is affected by human decisions and actions. Numerous decisions concerning animals are driven by human desires to enhance their own lives, and some of these decisions may be influenced by self-interest or a strong emphasis on economic factors. How to assess the welfare state of animals is a central issue in animal welfare science. Two critical questions can be used to address animal welfare: first, is the animal healthy, and second, does the animal have what it needs? Both of these questions can potentially be answered using the study of animal behavior. The development of behavioral methodologies is crucial for evaluating welfare in contexts where concern for animal welfare is often highest, such as on intensive modern farms and sites where working animals are used. Herein, we discuss animal welfare by focusing on some of its major concepts and explanations. Later, to illustrate key aspects of animal welfare, we chose to examine the information that is available for some 'neglected' livestock species, which are commercially important on a global basis and found in large numbers: buffaloes (Bubalus bubalis), camels (Camelus dromedarius), donkeys (Equus asinus), mules (Equus asinus × Equus caballus), and lumpfish (Cyclopterus lumpus). We chose these species because there are major ongoing concerns about their welfare, and more research is required to help solve the various problems. Overall, there are strong imbalances in terms of the species that are usually studied in terms of animal welfare research, and we call for greater attention to those that have traditionally been neglected.

Milk miRNA expression in buffaloes as a potential biomarker for mastitis.

BACKGROUND: Buffaloes have the highest potential for production due to a promising gene pool that is being enhanced and upgraded. Mastitis is a significant health impediment that greatly diminishes milk yield and quality, affecting rural farmers' livelihoods. The traditional gold standard used for diagnosing mastitis or subclinical mastitis is CMT, but it has the drawback of false positive or negative results. Subclinical mastitis, if not treated promptly, can lead to mammary tumors. To address the gap in early diagnosis of subclinical mastitis in CMT-negative milk of buffaloes, we performed a retrospective analysis and evaluated the milk miRNA expression profiles as potential biomarkers. RESULTS: Thirty buffalo milk samples based on clinical signs and CMT were divided into normal, subclinical, and clinical mastitis. SCC evaluation showed significant differences between the groups. The data analysis demonstrated that the elevation of miR-146a and miR-383 differed substantially between normal, subclinical, and clinical mastitis milk of buffaloes with 100% sensitivity and specificity. The relationship of SCC with miR-146a and miR-383 in normal/healthy and subclinical mastitis was positively correlated. CONCLUSION: The overexpression of miR-146a and miR-383 is associated with inflammation. It can be a valuable prognostic and most sensitive biomarker for early mastitis detection in buffaloes with SCC below 2 lakhs and CMT-ve, enhancing the accuracy of subclinical mastitis diagnosis.

Taurine dynamics in serum during the oestrous cycle in buffaloes.

Estrus identification is one of the common issues in buffaloes because of their short estrus duration and silent estrus problem. Hence, specific biomarkers facilitating in identifying the estrus stage would be helpful to buffalo farmers and researchers. In our previous studies, taurine, a non-protein amino acid that helps in the secretion of reproductive hormones such as GnRH, was found to be associated with postpartum anestrus in buffaloes. Therefore, the present study was conducted to explore the level of taurine in serum during different stages of the oestrous cycle in healthy cyclic buffaloes. Blood samples were collected from healthy cyclic buffaloes (n = 4), and taurine was estimated at the estrus (0th day), proestrus (-2nd day), metestrus (3rd day) and diestrus (+10th day) stages using TLC method. The days of the oestrous cycle were determined by ultrasonography and observation of behavioural signs by trained professionals. The results revealed that taurine was consistently present in the serum. However, the highest concentration of taurine was observed at the proestrus (0.20 ± 0.03 mg/mL) stage, which was greater (p < .05) than metestrus (0.10 ± 0.05 mg/mL) and diestrus (0.13 ± 0.03 mg/mL) stages, but comparable with the estrus stage. These results were also validated in the simulated population datasets of population size 6 to 10,000. Further, ROC curve analysis for the large simulated population indicated the efficiency of taurine to distinguish proestrus from metestrus and diestrus stages at a lower cutoff value of <0.1643 mg/mL with 60% sensitivity and specificity. Therefore, the present study concludes that serum taurine concentration could help in detecting proestrus stage of buffalo estrous cycle.

Effect of exogenous melatonin implant on post-thaw semen quality of buffalo bulls.

Melatonin is an intracellular antioxidant of sperm membrane that protects the cells from lipid peroxidation. Yet, its role as an antioxidant on semen quality of buffalo bulls is still obscure. The present study was undertaken to assess the effect of exogenous melatonin implant (18 mg/50 kg bodyweight) on post-thaw sperm characteristics, oxidative stress, endocrinological profiles and fertility of buffalo bulls. Six apparently healthy breeding Murrah buffalo bulls were randomly selected at bull farm, Guru Angad Dev Veterinary and Animal Sciences University for the present study and divided into two groups viz. control (n = 3) and melatonin implanted group (n = 3). A total of 120 ejaculates were collected from bulls of both groups (n = 60 each) throughout the study period. Most beneficial effects of melatonin implants were observed during post-implantation period. The percentages of post-thaw sperm total and progressive motility, viability and mitochondrial membrane potential were higher (p < .05) in melatonin implanted buffalo bulls compared to controls during post-implantation period. Following melatonin implantation, MDA production in post-thaw semen was lower (p < .05) in melatonin implanted group than in control group. Plasma melatonin and testosterone concentrations were higher (p < .05) in buffalo bulls implanted with melatonin as compared to their control counterparts. No differences (p > .05) in plasma LH concentrations were observed in both groups. First service pregnancy rate was 43.3% using semen of melatonin implanted bulls and 30.0% with semen of controls (p > .05). Thus, melatonin was able to protect sperm membrane against oxidative damage and improve post-thaw semen quality, thereby resulting in higher fertilizing potential of spermatozoa.

Effect of different concentrations of resveratrol on nuclear maturation and in-vitro development competence of oocytes of Nili Ravi buffalo.

Buffaloes are considered animals of the future with the ability to survive under unfavorable conditions. However, the lack of access to superior germplasm poses a significant challenge to increasing buffalo production. Resveratrol has been shown to improve oocyte quality and developmental competence in various animals during in vitro embryo development. However, limited information is available on the use of resveratrol to improve the in vitro maturation and development competence of Nili Ravi buffalo oocytes. Therefore, the current study aimed to investigate the influence of different concentrations of resveratrol on the maturation, fertilization, and development of buffalo oocytes under in vitro conditions. Oocytes were collected from ovaries and subjected to in vitro maturation (IVM) using varying concentrations of resveratrol (0 µM, 0.5 µM, 1 µM, 1.5 µM, and 2 µM), and the maturation process was assessed using a fluorescent staining technique. Results indicated no significant differences in oocyte maturation, morula rate, and blastocyst rate among the various resveratrol concentrations. However, the cleavage rate notably increased with 1 µM and 1.5 µM concentrations of resveratrol (p < 0.05). In conclusion, the study suggests that adding 1 µM of resveratrol into the maturation media may enhance the cleavage and blastocyst hatching of oocytes of Nili Ravi buffaloes. These findings hold promise for advancing buffalo genetics, reproductive performance, and overall productivity, offering potential benefits to the dairy industry, especially in Asian countries.

Dietary type (carnivore, herbivore and omnivore) and animal species modulate the nutritional metabolome of terrestrial species.

Ecometabolomics could be implemented as a powerful tool in molecular ecology studies, but it is necessary to know the baseline of certain metabolites and understand how different traits could affect the metabolome of the animals. Therefore, the main objective of this study was to provide values for the nutritional metabolome profile of different diet groups and animal species, as well as to study the differences in the metabolomic profile due to the effect of diet type and species. To achieve this goal, blood samples were taken from healthy animals (n = 43) of different species: lion (Panthera leo), jaguar (Panthera onca), chimpanzee (Pan troglodytes), bison (Bison bison), gazelle (Gazella cuvieri) and fallow deer (Dama dama), and with different types of diet (carnivore, herbivore and omnivore). Each blood sample was analysed to determine nutritional metabolites. The main results this study provides are the nutritional metabolic profile of these animals based on the type of diet and the animal species. A significant effect of the dietary type was found on nutritional metabolite levels, with those metabolites related to protein metabolism (total protein and creatine) being higher in carnivores. There is also an effect of the species on nutritional metabolites, observing a metabolome differentiation between lion and jaguar. In the case of herbivores, bison showed higher levels of uric acid and cholesterol, and lower urea levels than gazelle and fallow deer. More molecular ecology studies are needed to further the knowledge of the metabolism of these animals.

Calculation of livestock biomass and value by province in Indonesia: Key information to support policymaking.

Accurate estimations of the biomass and value of livestock in Indonesia are of great use in supporting investment decisions by the public and private sector and as a basis for estimating the losses due to animal disease. Biomass and the partial direct use value for key livestock species (cattle, buffalo, sheep, goats, pigs, chickens) for all provinces of Indonesia were derived from secondary data using a novel spreadsheet-based model. Using beef cattle as an example, we also explored the use of a herd dynamics model to validate base data on populations and productivity used to generate biomass values, and these were found to be generally robust. Total partial direct use value of livestock is estimated to be almost USD54 billion in 2021, comprising almost USD33 billion of population value and almost USD21 billion of production value. Beef cattle account for 44% of total value and chicken (broiler, layer and native chickens) account for a further 36% of the total. Breaking the data down by province reveals the regional importance of some livestock types that are of relatively minor importance nationally (pigs in East Nusa Tenggara and sheep in West Java). It also reveals the importance of livestock in the poorest provinces of Indonesia, where livestock acts as a store of wealth and serves socio-cultural purposes.

Reemerging/Notifiable Diseases to Watch.

Reemerging and notifiable diseases of cattle and bison continue to pose potential risks to their health and lives and affecting production and the livelihoods of producers. It is essential to understand the clinical presentation of these diseases to watch for possible incursions and infections and to immediately report your suspicions to your State and Federal Animal Health Officials. Three of these reemerging and notifiable diseases of cattle and bison, malignant catarrhal fever, bluetongue virus, and New World screwworm, are presented in this article for increased awareness to consider as a differential if examinations present suggestive clinical signs.

Susceptibility of Mediterranean Buffalo (Bubalus bubalis) following Experimental Infection with Lumpy Skin Disease Virus.

Lumpy skin disease (LSD) is a viral disease of cattle and water buffalo characterized by cutaneous nodules, biphasic fever, and lymphadenitis. LSD is endemic in Africa and the Middle East but has spread to different Asian countries in recent years. The disease is well characterized in cattle while little is known about the disease in buffaloes in which no experimental studies have been conducted. Six buffaloes and two cattle were inoculated with an Albanian LSD virus (LSDV) field strain and clinically monitored for 42 days. Only two buffaloes showed fever, skin nodules, and lymphadenitis. All samples collected (blood, swabs, biopsies, and organs) were tested in real-time PCR and were negative. Between day 39 and day 42 after inoculation, anti-LSDV antibodies were detected in three buffaloes by ELISA, but all sera were negative by virus neutralization test (VNT). Cattle showed severe clinical signs, viremia, virus shedding proven by positive real-time PCR results, and seroconversion confirmed by both ELISA and VNT. Clinical findings suggest that susceptibility in buffaloes is limited compared to in cattle once experimentally infected with LSDV. Virological results support the hypothesis of buffalo resistance to LSD and its role as an accidental non-adapted host. This study highlights that the sensitivity of ELISA and VNT may differ between animal species and further studies are needed to investigate the epidemiological role of water buffalo.

Doppler ultrasonographic scan, gene expression and serum profile of immune, APPs and antioxidant markers in Egyptian buffalo-cows with clinical endometritis.

The objective of this study was to elaborate Doppler ultrasonographic scan, genetic resistance and serum profile of markers associated with endometritis susceptibility in Egyptian buffalo-cows. The enrolled animals were designed as; twenty five apparently healthy buffalo-cows considered as a control group and twenty five infected buffalo with endometritis. There were significant (p < 0.05) increased of cervical diameter, endometrium thickness, uterine horn diameter, TAMEAN, TAMAX and blood flow through middle uterine artery with significant decrease of PI and RI values in endometritis buffalo-cows. Gene expression levels were considerably higher in endometritis-affected buffaloes than in resistant ones for the genes A2M, ADAMTS20, KCNT2, MAP3K4, MAPK14, FKBP5, FCAMR, TLR2, IRAK3, CCl2, EPHA4, and iNOS. The RXFP1, NDUFS5, TGF-ß, SOD3, CAT, and GPX genes were expressed at substantially lower levels in endometritis-affected buffaloes. The PCR-DNA sequence verdicts of healthy and affected buffaloes revealed differences in the SNPs in the amplified DNA bases related to endometritis for the investigated genes. However, MAP3K4 elicited a monomorphic pattern. There was a significant decrease of red blood cells (RBCs) count, Hb and packed cell volume (PCV) with neutrophilia, lymphocytosis and monocytosis in endometritis group compared with healthy ones. The serum levels of Hp, SAA, Cp, IL-6, IL-10, TNF-α, NO and MDA were significantly (P˂0.05) increased, along with reduction of CAT, GPx, SOD and TAC in buffalo-cows with endometritis compared to healthy ones. The variability of Doppler ultrasonographic scan and studied genes alongside alterations in the serum profile of investigated markers could be a reference guide for limiting buffalo endometritis through selective breeding of natural resistant animals.

Putative bloodmeal sources in Glossina austeni tsetse fly of Arabuko Sokoke National Reserve in Kenya.

Tsetse flies, the sole biological vectors of trypanosomiasis, are predominantly controlled using visual traps and targets baited with attractant lures. Formulation of the lures is informed by compositions of odors from vertebrate hosts preferred by specific tsetse species. However, there are no effective lures for Glossina austeni, a major vector of trypanosomiasis along eastern-coastal region of Africa. Formulation of the lure can be informed by knowledge of G. austeni, preferred vertebrate hosts. We thus sought to understand these hosts by assessment of putative bloodmeal sources of this tsetse fly in Arabuko Sokoke National Reserve where this species is naturally present. We sampled tsetse flies using NGU traps, isolated non-teneral G. austeni flies based on their feeding status, and identified vertebrate source of bloodmeals in their midgut contents using vertebrate 16S rRNA-PCR High-Resolution Melting analysis. We analyzed the relative vertebrate species frequencies in the bloodmeals using Fisher's exact tests. Overall, we trapped 122 flies, most of which (66.39%) were non-teneral, among which we successfully identified the vertebrate bloodmeals in 30 samples. Specifically, we detected putative suni antelope (Neotragus moschatus), harnessed bushbuck (Tragelaphus scriptus), buffalo (Syncerus caffer) and cattle (Bos taurus) derived bloodmeals. Putative suni antelope bloodmeals were significantly more frequent (63.22%), than those of the harnessed bushbuck (23.33%), buffalo (10.00%) or cattle (3.33%) (p < 0.05 Fisher's exact tests) among the samples analyzed. Suni antelope thus appears to predominate vertebrate bloodmeal source for G. austeni in the reserve, coincident with findings reported elsewhere, and is therefore a viable candidate for bioprospecting for G. austeni responsive attractants.

Genome-wide diversity, population structure and signatures of inbreeding in the African buffalo in Mozambique.

The African buffalo, Syncerus caffer, is a key species in African ecosystems. Like other large herbivores, it plays a fundamental role in its habitat acting as an ecosystem engineer. Over the last few centuries, African buffalo populations have declined because of range contraction and demographic decline caused by direct or indirect human activities. In Mozambique, historically home to large buffalo herds, the combined effect of colonialism and subsequent civil wars has created a critical situation that urgently needs to be addressed. In this study, we focused on the analysis of genetic diversity of Syncerus caffer caffer populations from six areas of Mozambique. Using genome-wide SNPs obtained from ddRAD sequencing, we examined the population structure across the country, estimated gene flow between areas under conservation management, including national reserves, and assessed the inbreeding coefficients. Our results indicate that all studied populations of Syncerus caffer caffer are genetically depauperate, with a high level of inbreeding. Moreover, buffaloes in Mozambique present a significant population differentiation between southern and central areas. We found an unexpected genotype in the Gorongosa National Park, where buffaloes experienced a dramatic population size reduction, that shares a common ancestry with southern populations of Catuane and Namaacha. This could suggest the past occurrence of a connection between southern and central Mozambique and that the observed population structuring could reflect recent events of anthropogenic origin. All the populations analysed showed high levels of homozygosity, likely due to extensive inbreeding over the last few decades, which could have increased the frequency of recessive deleterious alleles. Improving the resilience of Syncerus caffer caffer in Mozambique is essential for preserving the ecosystem integrity. The most viable approach appears to be facilitating translocations and re-establishing connectivity between isolated herds. However, our results also highlight the importance of assessing intraspecific genetic diversity when considering interventions aimed at enhancing population viability such as selecting suitable source populations.

Study on the Ixodid ticks species diversity (Acari: Ixodidae) on domestic ruminants in different agro-climatic regions of Tamil Nadu.

A survey of Ixodid tick species diversity on domestic ruminants was conducted in seven agro-climatic regions of Tamil Nadu State, India. Tick surveys were conducted on domestic ruminants such as cattle, buffalo, sheep, and goat in seven districts of Tamil Nadu. The overall tick infestation was 38.8%, 5.8%, 14.6%, and 40.8% on cattle, buffaloes, sheep, and goats, respectively. A total of 8068 ticks from 18 species belonging to four genera were recorded. Overall, Haemaphysalis intermedia was the predominant (51.38%) tick species which has a wide host range. The most prevalent tick species in cattle and buffalo were Rhipicephalus (B.) microplus (25.41%) and Rhipicephalus haemaphysaloides (56.69%), respectively. Haemaphysalis intermedia was the most prevalent in ticks in sheep (70.35%), goat (70.35%), and dog (55.79%). In the present study, local anomalies such as the ectromely of one leg and the absence of adanal plates were observed in Rh. haemaphysaloides. The study also found that local anomaly such as protuberances in the hind tarsal and atrophy of the adanal plate was observed in Rhipicephalus (Boophilus) microplus. In addition, a general anomaly with three atrophy caudal appendages was also observed in Rhipicephalus (Boophilus) microplus. The overall prevalence of anomalies in Rh. haemaphysaloides and Rh. (B.) microplus was 0.3% (3/971) and 0.4% (3/678), respectively.

Supplementation with long-acting injectable progesterone 3 days after TAI impaired luteal function in buffaloes.

Three experiments were conducted to evaluate the effects of long-acting injectable progesterone (iP4) in buffalo cows. In Experiment 1, ovariectomized buffaloes received 300 mg (iP300) or 600 mg (iP600) of iP4, and serum P4 concentrations were evaluated. In experiment 2, three groups were compared: control or administration of 300 mg of iP4 3 (iP4-D3) or 6 days (iP4-D6) after timed artificial insemination (TAI). On day 16, reproductive tract was recovered for conceptus, endometrium, and corpus luteum (CL) analysis. In experiment 3, pregnancy per AI (P/TAI) and proportion of pregnancy losses were evaluated after administration of 300 mg of iP4 3 (iP4-D3) or 6 days (iP4-D6) after TAI in lactating buffaloes. In experiment 1, serum P4 concentrations remained over 1 ng/mL for ~ 3 days in both groups. The 300 mg dose was used in subsequent experiments. In experiment 2, CL weight and endometrial glands density were decreased, and conceptus length was increased in iP4-D3 compared to control and to iP4-D6 (P < 0.05). Transcript abundance of Prostaglandin F Receptor (FP) and ISG15 in CL and of ISG15 and MX1 in endometrium was greater in iP4-D3 when compared to control and to iP4-D6 (P < 0.05). In experiment 3, there was no difference among experimental groups for P/TAI at D30 and pregnancy losses (P > 0.1); however, iP4-D3 presented a lower P/TAI at day 60 (41.7%) when compared to control (56.8%) and iP4-D6 (57.7%; P = 0.07). In conclusion, administration iP4 at 3 days after TAI affects CL development and consequently decreases final pregnancy outcome in buffaloes.

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.

Niche overlap across landscape variability in summer between two large herbivores using eDNA metabarcoding.

Understanding the relationship between a species feeding strategy and its environment (trophic ecology) is critical to assess environmental requirements and improve management policies. However, measuring trophic interactions remains challenging. Among the available methods, quantifying the plant composition of a species' diet indicates how species use their environment and their associated niche overlap. Nevertheless, most studies focusing on herbivore trophic ecology ignore the influence that landscape variability may have. Here, we explored how landscape variability influences diet composition through niche overlap. We used eDNA metabarcoding to quantify the diet composition of two large herbivores of the Bialowieza Forest, red deer (Cervus elaphus) and European bison (Bison bonasus) to investigate how increasing habitat quality (i.e. higher abundance of deciduous forage species) and predation risk (i.e. density of wolf in the area) influence their diet composition and niche partitioning. Our findings indicate diet composition is non-homogeneous across the landscape, both within and between species. Red deer showed greater diet variability and lower niche overlap within species compared to bison. We detected a reduction of niche overlap for red deer with increasing predation risk, leading to more dissimilar diets, suggesting their feeding behaviour is affected by wolf presence. This correlation was not found for bison, which are rarely predated by wolf. Higher habitat quality was associated with higher niche overlap only within bison, probably due to their suboptimal feeding strategy as browsers. These results show the importance of integrating environment-induced diet variation in studies aimed at determining the landscape usage or niche overlap of a species.

Diversity and antigenic potentials of Mycoplasmopsis bovis secreted and outer membrane proteins within a core genome of strains isolated from North American bison and cattle.

Mycoplasmopsis bovis is a worldwide economically important pathogen of cattle that can cause or indirectly contribute to bovine respiratory disease. M. bovis is also a primary etiological agent of respiratory disease in bison with high mortality rates. A major challenge in the development of an efficacious M. bovis vaccine is the design of antigens that contain both MHC-1 and MHC-2 T-cell epitopes, and that account for population level diversity within the species. Publicly available genomes and sequence read archive libraries of 381 M. bovis strains isolated from cattle (n = 202) and bison (n = 179) in North America were used to identify a core genome of 575 genes, including 38 that encode either known or predicted secreted or outer membrane proteins. The antigenic potentials of the proteins were characterized by the presence and strength of their T-cell epitopes, and their protein variant diversity at the population-level. The proteins had surprisingly low diversity and varying predictive levels of T-cell antigenicity. These results provide a reference for the selection or design of antigens for vaccine testing against strains infecting North American cattle and bison.

Effects of Pregnancy Prevention on Brucella abortus Shedding in American bison (Bison bison).

Products of parturition are the predominant source of Brucella abortus for transmission in bison (Bison bison). Our objective was to assess whether preventing pregnancy in Brucella-seropositive bison reduced B. abortus shedding. Brucella-seropositive and -seronegative bison from Yellowstone National Park, Wyoming, USA were used in a replicated experiment. Each of two replicates (rep1, rep2) included a group of seropositive females treated with a single dose of gonadotropin-releasing hormone-based immunocontraceptive (Treatment rep1, n=15; Treatment rep2, n=20) and an untreated group (Control rep1, n=14; Control rep2, n=16) housed separately. Seronegative sentinel females were placed in each group to monitor horizontal transmission. Seronegative males were co-mingled for breeding each year. Pregnant females were removed from treatment groups in the first year, but not thereafter. Each January-June we monitored for B. abortus shedding events-any parturition associated with culture-positive fluids or tissues. We analyzed probability of shedding events using a negative binomial generalized linear mixed model fit by maximum likelihood using Laplace approximation. Over 5 yr, we observed zero shedding events in Treatment rep1 vs. 12 in Control rep1. All five Control rep1 sentinels but zero (0/5) Treatment rep1 sentinels seroconverted. In the second replicate, Treatment rep2 had two shedding events over 3 yr and Control rep2 had five events over 2 yr. Sentinels in both Control rep2 (3/6) and Treatment rep2 (5/6) seroconverted by trial endpoint. Treatment rep1 showed a reduced shedding probability relative to Control rep1, Treatment rep2, and Control rep2 (log odds value -25.36 vs. -1.71, -1.39, and -0.23, respectively). Fixed effect predictor covariates, year and age, had no explanatory value. These data suggest that successful contraception of brucellosis-seropositive female bison prevents shedding of B. abortus by individual animals. However, contraceptive treatment may or may not sufficiently reduce disease transmission to reduce brucellosis prevalence in an affected herd.