Limited effects of oral drench of mineral supplement for treating Mycoplasma bovis in mixed-sex bison (Bison bison) yearlings

Trace minerals found in the diet are essential for animal health, but the role of mineral supplementation in maintaining bison health or boosting immune response is relatively unknown. This study evaluated the impact of an oral drench supplement containing Co, Cu, Se, and Zn—minerals associated with immune function—in reducing mortality and maintaining health in response to a Mycoplasma bovis outbreak in yearling bison. A total of 1,295 mixed-sex, non-reproductive yearlings were studied, with 464 receiving the supplement and 831 serving as controls. Mortality totaled 238 individuals (18.4%), with no statistically significant difference between groups (Pearson’s χ² test, p>0.05), indicating supplement ineffectiveness. Blood analysis confirmed no change in mineral status, suggesting that the supplement formulation, intended for cattle, may not meet bison-specific requirements. Water quality analysis of water sources used in the study revealed elevated Fe and manganese levels, but other mineral imbalances were not evident. Growth rates and final weights did not differ significantly between treatment and control groups, although males consistently outweighed females. Parasitological analyses showed minor differences in gastrointestinal nematode burdens, with no apparent link to supplementation or mortality. Serology results indicated significant differences but were likely of limited biological relevance. Finally, the study highlighted the potential implications of frequent bison handling for research or other purposes, which may increase stress and disease susceptibility. These findings underscore the need for bison-specific mineral information, as well as diagnostic, prevention, and treatment strategies to improve health management in this species.

1 Introduction

Two major issues continue to affect health management of North American bison (Bison bison): limited information on mineral requirements and best practices for disease mitigation. According to USDA, on average, 61% of all bison deaths are due to natural causes such as “diseases, disorders, or other health problems” (USDA–APHIS–VS−CEAH–NAHMS, 2016, 2025). In other species, supplemental minerals known to improve immune function help mitigate health-related issues (O’Dell and Sunde, 1997; National Research Council, 2007; NASEM, 2016); however, mineral requirements in bison remain unresolved (Huntington et al., 2019). Lack of information on mineral requirements results in widely variable mineral supplementation regimes that can often end up as costly endeavors (e.g., unused or overused minerals) that mislead other managers to conduct similar misguided practices. Moreover, because mineral requirements are unresolved in bison, managers often apply practices seen as helpful in beef cattle without known benefit in bison (Dyer et al., 2008).

A common issue affecting bison health and production is the periodic reoccurrence of Mycoplasma bovis, a respiratory bacterial infection associated with caseonecrotic pneumonia, laryngitis, and arthritis often resulting in sepsis, multiple-organ involvement, synovial joint inflammation (e.g., lameness (Dyer et al., 2008; Janardhan et al., 2010)), mass wasting (e.g., declining body condition (Register et al., 2018; Martin and Daly, 2022)), and, ultimately, death (e.g., anecdotally, herd mortality averages approximately between 10% and 20% with rare cases upwards to 50% (Janardhan et al., 2010; Martin and Daly, 2022; Matheson et al., 2024)). Effective diagnostic, treatment, and prevention practices are lacking in bison. Despite vaccine availability, survival rates between vaccinated and unvaccinated animals are equivocal (Perez-Casal et al., 2017; Prysliak et al., 2023). Longer-term, infected surviving individuals were observed to have abortions and male infertility (Dyer et al., 2008, 2013; Janardhan et al., 2010; Woodbury and Windeyer, 2011; Register et al., 2013, 2021). Anecdotal observations from bison managers indicate that M. bovis outbreaks may be related to 1) persistent and chronic smoke/aerosol particulate matter or long-term drought, 2) heat waves as defined by 3+ consecutive days of consistently hot, windy, dry weather, 3) persistent presence of the disease in the environment or nasal passages waiting for outbreak factors including suppressed immune function, 4) high loads of gastrointestinal nematodes, 5) stress (e.g., moving or handling animals), or especially 6) any combination thereof.

Handling semi-wild and wild ungulates is challenging for many operations; handling-related mortality rates range between 7.2% and 86% for white-tailed deer (Odocoileus virginanus (Delgiudice et al., 2001; Kautz et al., 2020)) and 17.8% for pronghorn antelope (Antilocapra americana (Jacques et al., 2009)). Overall, “handling-related” bison mortalities are seemingly within the range of wildlife species at approximately 12.6% (USDA–APHIS–VS−CEAH–NAHMS, 2016, 2025), whereas beef cattle lack “handling-related” attribution altogether but attribute “lameness or injury” to account for 6.4% of all mortalities (USDA–APHIS–VS−CEAH–NAHMS, 2010). Therefore, bison managers are often averse to handling bison more than once annually, limiting intervention treatment options. For example, administration of intervention antibiotic treatment is fairly common, on average, 51.8% of US beef cattle cow/calf operations report doing so as compared to 13.9% of US bison cow/calf operations (USDA National Animal Health Monitoring System, 2020; USDA–APHIS–VS−CEAH–NAHMS, 2025).

Here, we evaluate the efficacy of an oral drench mineral supplementation of Co, Cu, Se, and Zn. These microminerals have broad influence on metabolic processes that range from antioxidant protection, normal reproduction, and growth and development (O’Dell and Sunde, 1997; National Research Council, 2007; NASEM, 2016). These four specifically were chosen for formulation due to their roles within immunity affecting enzymatic activity associated with DNA replication, energy metabolism, and cellular dependent synthesis (Sager, 2014). In particular, Co has been shown to increase antibody response in beef cattle (Sager, 2014). This study sought to reduce mortality from M. bovis infection, as well as the downstream effects of treatment on growth, gastrointestinal nematode abundance and diversity, mineral uptake in the bloodstream, and other serologically identified disease infections in yearling bison with this oral drench.

2 Materials and methods

2.1 Study site

This study was conducted in the summer of 2021 at the Turner Institute of Ecoagriculture (“Institute”) McGinley Ranch near Gordon, Nebraska. The landscape is geologically dominated by rolling Sandhills on the western South Dakota–Nebraska border with dry upland native grass pastures interspersed with moist lowland meadows supporting typical mixed-grass prairie rangeland species. Grazing is adaptively managed by rotating two bison herds—a main cow/calf herd and weaned yearling feeders (this study group; n=1295) destined for meat slaughter—through 140 pastures across approximately 80,000 acres. Over the last decade, this property has experienced periodic outbreaks of M. bovis approximately every 3 years (TKB, pers. obs.).

Water is provided to the animals through a series of shallow groundwater wells and tanks throughout each pasture, and/or abundant surface water in ponds, wetlands, and small drainages. Water quality was assessed at six water sources in pastures grazed by the study animals through ServiTech (Hastings, NE). Total dissolved solids, nitrate/nitrite, nitrogen, sulfate, total sulfur, total sodium, chloride, total calcium, total magnesium, total potassium, total iron, total manganese, hardness (CaCO₃), total boron, total copper, total molybdenum, total zinc, electrical conductivity, and acidity (pH) were tested.

2.2 Study design

In this study of 1,295 yearling weaned bison, 620 were female (47.9%) and 675 were male (52.1%). This study administered a viscous liquid mineral amino acid chelate oral drench supplement (Bovi-Trace^™, Creative Science^® (formerly KineticVet); hereafter referred to as “supplement”). The supplement was administered as an unmatched case–control design to 464 (35.8% of total) randomly assorted mixed-sex yearling bison at two times during the study, early May and early August 2021. There were 216 females and 248 males in the treatment group and 404 females and 427 males within the control (e.g., unsupplemented) group. The supplement was composed of 15 mg/mL zinc (Zn), 15 mg/mL copper (Cu), 2 mg/mL selenium (Se), and 2 mg/mL cobalt (Co), at a dosage of 0.088 mL/kg of BW. These specific concentrations were selected to function as a “pulse dose,” utilizing standard levels for bovine (cattle) oral drenches to ensure rapid absorption following a single administration event, contrasting with lower-concentration daily maintenance formulations (Jackson et al., 2020). The yearlings were otherwise unsupplemented, were not given anthelmintics during the study, and were selected into the study by administering the supplement to every second animal through the chute in a handling corral facility. Over the study period from May to November 2021, body mass was measured on all individuals (pre-study body mass was taken in January 2021) and subsampled (n=106, equally split among control and treatment groups) for fecal parasite load and diversity, blood mineral levels, and blood serology in early May, early August, and early November 2021. The yearlings averaged 182 ± 25 kg (n =1295) in January, 194 ± 26 kg (n =1290) in May, 249 ± 29 kg (n =1278) in August, and 285 ± 31 kg (n =1064) in November. The average dose in May and in August increased with average body weight, from 17.1 mL per head to 22.0 mL per head (Table 1).

Table 1

Table 1. Concentration of trace mineral in product used and dosage of trace mineral treatment.

2.3 Measures of health

During the study, body mass (kg) of each individual (n =1,064 with all four weight measurements) was measured on a digital load-cell squeeze chute scale (Berlinic Manufacturing, Quill Lake, Saskatchewan, Canada) at each sampling event. Fecal grabs were collected from the rectum of the same individual bison subsampled during each sampling period to analyze gastrointestinal nematodes (i.e., helminths) using the Wisconsin sugar floatation technique (reported as eggs per gram, EPG) to identify and quantify eggs, and homogenized pooled sampling coproculture to hatch, identify, and quantify strongyle larvae (reported as larvae per gram, LPG) at the Texas A&M University Parasitology Diagnostic Laboratory (College Station, TX). Blood was collected from the same subsampled individuals, and blood serum was analyzed for trace mineral concentrations for Ca, Co, Cr, Cu, Fe, K, Mg, Mn, Mo, Na, P, Se, and Zn at the Kansas State Veterinary Diagnostic Laboratory (Manhattan, KS) during each sampling event. During the start and end sampling events, May and November, serum was analyzed using commercially available assays for Anaplasma (ELISA; VMRD, Pullman, WA), Bluetongue virus (ELISA; VMRD, Pullman, WA), bovine respiratory syncytial virus (serum neutralization; in-house and follows Rose et al. (1986)), bovine viral diarrhea virus type 1 (≈Pestivirus A, serum neutralization; in-house and follows Rose et al. (1986)), bovine viral diarrhea virus type 2 (≈Pestivirus B, serum neutralization; in-house and follows Rose et al. (1986)), infectious bovine rhinotracheitis (≈Bovine herpesvirus-1, serum neutralization; in-house and follows Rose et al. (1986)), bovine parainfluenza-3 virus (serum neutralization; in-house and follows Rose et al. (1986)), epizootic hemorrhagic disease virus (agarose gel immunodiffusion, AGID; in-house and follows Torchetti et al. (2024); only ran if Bluetongue virus is negative), and Mycoplasma bovis (PCR molecular diagnostic; MPX Multiplex One-Step Mastermix, Life Technologies; primers and probes, Integrated DNA Technologies following Clothier et al. (2010); pooled samples of 5 to identify retest of positive individual samples) at the American Association of Veterinary Laboratory Diagnosticians-accredited Animal Disease Research and Diagnostic Laboratory at South Dakota State University (Brookings, SD).

2.4 Ethical review of study

Animals in this study remained under ownership and care of the Institute at McGinley Ranch and were under constant oversight of a permanent on-site manager working in consultation with Institute veterinarian (coauthor TKB). The studies involving animals were reviewed and approved by the South Dakota State University Institutional Animal Care and Use Committee [exemption permit: 2102-013A].

2.5 Data analysis

All data computation and statistical analyses were conducted in Stata SE (v19.0; College Station, Texas). Differential mortality rates, incidence rates, odds ratios, Pearson’s χ² test, risk ratios, and were analyzed using respective “epitab” functions in Stata. Differences in blood serum mineral concentrations, blood serum serological results, and parasitological abundances were evaluated using t-tests or Kruskal–Wallis tests, and figures show 95% CI using quadratic regressions. Results discussed will be in reference to both males and females mixed, unless otherwise denoted.

3 Results

3.1 Study site: water quality

Ultimately, only total Fe, Mn, and pH were potentially problematic with moderate to high levels relative to data available from species other than bison (O’Dell and Sunde, 1997; NASEM, 2016). Acidity, measured as pH, was moderately on the high side averaging 7.94 ± 0.27, approaching the upper tolerance of 8.0. The preferred pH range for drinking water for beef cattle (Bos taurus) ranges between 6.0 and 8.0, whereas other species can tolerate up to 8.3 (Morgan, 2011). Water Fe averaged 0.435 ± 0.36 mg/L, Mn averaged 0.148 ± 0.09 mg/L, Zn averaged 0.045 ± 0.01 mg/L, and Cu concentrations were below detection levels.

3.2 Mortality: M. bovis infection

An opportunistic study of a Mycoplasma bovis outbreak was conducted on the study herd of weaned-yearling bison. In total, 238 of the 1,295 yearlings (18.4%) died during the study period. A breakdown of these mortalities by treatment group and sex is provided in Table 2. Of the total mortalities, 149 occurred in the control group and 89 in the supplement treatment group. When examined by sex, 110 of the deceased were female (46.2%) and 128 were male (53.8%). Within the control group, these mortalities comprised 71 females and 78 males, while the treatment group consisted of 39 females and 50 males.

Table 2

Table 2. Two-way summary table of dead and alive animals by treatment or control group over sex.

3.3 Case–control odds ratio results

There was no statistically significant association between receiving the mineral supplement and mortality due to M. bovis (Pearson’s χ² = 0.31, p=0.58). The odds of mortality were 9% higher for treatment animals than for control animals, although this finding was not statistically significant (OR=1.09, 95% CI: 0.81-1.45). After adjusting for sex, the supplement’s efficacy was −6.8% (p=0.60), indicating a non-significant 6.8% increase in mortality risk. The 95% confidence interval was wide, ranging from an 18.5% risk reduction to a 32.1% risk increase, confirming the lack of discernible effect.

3.4 Growth and end of study weight

T-tests showed that average daily gain (ADG; kg/day) and end-of-study weight (kg) were not statistically different between the control and treatment groups for neither males nor females (p > 0.05). However, significant differences between sexes were evident throughout the study, with males being consistently larger than females (p ≤ 0.01). Over the entire study period, the average female ADG was 0.32 ± 0.01 kg/day, while the average male ADG was 0.37 ± 0.01 kg/day. The end-of-study weights averaged 271.6 ± 1.2 kg for the 512 surviving females and 297.3 ± 1.3 kg for the 548 surviving males. A logistic growth curve was used to model the growth period for these yearlings (Supplementary Figure S1). Ultimately, the supplement had no discernible effect on weight gain for either sex compared to the control group.

3.5 Parasitology: gastrointestinal nematodes

Fecal parasitological analyses revealed minimal difference between treatment and control groups during the study (p > 0.05). Data are summarized in Figure 1 and Supplementary Table S1. However, some control individuals showed slightly elevated parasite burdens compared to their treatment counterparts (Figure 1).

Figure 1

Figure 1. Panel of fecal parasite burdens over the study period by control (open purple circles) and treatment (filled green triangles) groups with fitted quadratic relationship. Bison that died by the end of the study are indicated with black “×” (these are “jittered” to show density).

3.6 Mineralogy: blood mineral concentrations

Summary statistics for all 13 mineral concentrations from blood serum at the start, middle, and end of the study are presented in Supplementary Table S2. Additional details are provided on the four minerals in the drench treatment: Co, Cu, Se, and Zn (Figure 2), as well as K and Fe. There were no significant differences between treatment and control groups in both sexes combined in the blood concentrations of the minerals provided in the drench formulation (Figure 2).

Figure 2

Figure 2. Blood serum mineral concentrations for cobalt (upper left), copper (upper right), selenium (lower left), and zinc (lower right) over the study (Julian Day) by treatment (filled green triangle) and control (open purple circle) groups of bison with those that died by the end of the study indicated with black “×” (these are “jittered” around the day of year to show density). Individuals present above the upper threshold (black horizontal line) indicate possible toxic levels of that mineral and those below the lower threshold (gray horizontal line) indicate possible deficient levels of that mineral.

3.6.1 Cobalt (Co)

At the beginning of the study, there were no differences in control/treatment groups. However, males had slightly more blood Co (mg/mL, Supplementary Table S2; Figure 2 upper left) concentration than females (0.0017 vs. 0.0014, respectively; p=0.02). At the end of the study, however, males showed a difference between treatment and control groups (0.0015 vs. 0.0012, respectively; p=0.003).

3.6.2 Copper (Cu)

At the beginning of the study, there were no differences in Cu (mg/mL) blood serum concentrations across treatments. In the middle of the study, at second administration of the mineral supplement, serum Cu was higher in the treatment group than the control (Figure 2 upper right). At the end of the study, there was only a difference in females between treatment and control groups (0.99 vs. 0.86, respectively; p =0.02).

3.6.3 Selenium (Se)

No differences between the control and treatment groups for Se (mg/mL, Supplementary Table S2; Figure 2 lower left) at the beginning of the study nor at the end of the study (p > 0.05). Although anecdotal, some individuals were above 0.14 ppm.

3.6.4 Zinc (Zn)

At the beginning of the study, males had slightly less blood Zn (mg/mL, Supplementary Table S2; Figure 2 lower right) concentration than females (1.85 ppm vs. 1.99 ppm, respectively; p =0.02). No differences were apparent at the end of the study (p > 0.05).

3.6.5 Other minerals (K and Fe)

Potassium (mg/mL; Figure 3; Supplementary Tables S2 & S3) blood serum concentrations were significantly different at the end of the study between euthanized animals and those that lived to the end of the study (517.3 vs. 396.2; p=0.008; Supplementary Table S3). Above 550 mg/mL, K is indicative of hyperkalemia in large ruminants (Constable, 2021), and several individual bison were approaching and exceeding this threshold in both the euthanized and alive groups.

Figure 3

Figure 3. Blood serum potassium concentrations between bison (n=300) that died (black “×”; these are “jittered” around the day of year to show density) and were alive (open blue squares). Individuals measuring above the horizontal solid black line indicates increasing probability of hyperkalemia (>550 mg/mL).

Iron (mg/mL) levels averaged 2.9 ± 1.3 mg/mL (Figure 4), exceeding 2.5 mg/mL upper threshold (NASEM, 2016). High levels of Fe may be due to the high levels in the drinking water and may be antagonistic for other mineral absorption and use, especially for Cu, Mn, and Zn. Particularly, Zn appears to decline throughout the study (Figure 2, lower right).

Figure 4

Figure 4. Blood serum iron concentrations between bison (n=300) that died (black “×”; these are “jittered” around the day of year to show density) and were alive in the control group (open purple circles) and alive in the treatment group (filled green triangles). Individuals measuring above the horizontal solid black line indicates increasing probability of hemochromatosis (>2.5 mg/mL).

3.7 Serology: blood titers

Blood serological analyses revealed minimal observable differences and no significant differences between treatment and control groups throughout the study. Data are summarized in Figure 5 and Supplementary Table S4 (p > 0.05).

Figure 5

Figure 5. Panel of serological titer presence prevalence (proportion positive) over the study period by control (open purple circles) and treatment (filled green triangles) groups with fitted linear relationships. Bison that died by the end of the study are indicated with black “×” (these are “jittered” around the day of year to show density).

4 Discussion

Efficacy of the Cu, Co, Zn, and Se oral drench mineral supplement to abate M. bovis-related mortality in yearling bison was −6.8% and is not recommended as a therapeutic practice to prevent or reduce the impact of an M. bovis outbreak in yearling bison. Stress from extreme weather (repeated heat waves and persistent wildfire smoke) were likely confounding factors with M. bovis, and the repeated handling of the study animals in corrals and a squeeze chute to deliver the mineral supplement and collect samples may have added undue stress that triggered or enhanced the severity of the M. bovis outbreak, ultimately complicating effectiveness of the treatment. In hindsight, there should have been another “control” group that was not exposed to handling stress to assess the effect of that variable on mortality due to M. bovis. Beyond being a limitation of this study design, this outcome itself may be a substantive finding. Our experience suggests that intensive handling of semi-wild animals may act as a significant iatrogenic risk factor, potentially triggering or exacerbating disease outbreaks, particularly when co-occurring with other environmental stressors like heat waves and wildfire smoke (Supplementary Figure S2). This highlights critical consideration for managers, who must weigh the perceived benefits of intervention against the potential for stress-induced disease susceptibility in bison herds. The oral drench mineral supplement made no difference in growth within sex groups (Figure 1). The supplement also appears to not have made a difference in blood serum mineral concentrations (Figure 2), but it remains unknown if there was a difference in the mineral concentrations of the liver, a critical mineral storage depot. Furthermore, the supplement made no difference in reducing mortality as indicated by measures of a negative efficacy of −6.8% and low odds ratio of 1.08 (Table 2).

From the beginning to the end of the study, serum trace mineral levels were not different between the treatment and control groups. However, at the beginning of the study, several individuals approached or exceeded toxic ranges—as defined for beef cattle—for Zn, Mn, and Mo. By the end of the study, many individuals approached or exceeded toxic ranges for Ca and Se. Iron content was high throughout the entire study. Drinking water sources likely contributed to high Mn and Fe levels because they were measured at naturally high levels in the drinking water, 0.148 and 0.435 mg/L, respectively. In contrast, while drinking water was low in Cu and Zn, blood serum Cu and Zn levels appeared relatively normal prior to administering the treatment. These data suggest that thresholds developed on beef cattle may be different than that of bison and therefore remain unresolved. Literature in beef cattle suggests that the high levels of some minerals seen in this study can serve as antagonists of each other (NASEM, 2016). In particular—and relevant to this study—both Ca and Mn can work antagonistically in each other’s absorption rates. It has been reported that high levels of Ca and P may decrease the availability of dietary Mn. Low Vitamin E can also have a significant impact on Se usage (NASEM, 2016). Both toxic and deficient levels of Fe are known to create Cu deficiencies (NASEM, 2016). Sulfur also plays a role in Se metabolism and should be noted, although there is no evidence of excess S in the diets of the animals in this study. Future studies are needed to better understand nutritional requirements of bison and micronutrient interrelations. Liver samples would also be beneficial in future studies as it is a major storage site for many vitamins and minerals (NASEM, 2016). While the high Fe levels in drinking water provide the most parsimonious explanation for the elevated serum iron observed throughout the study, the potential for the M. bovis infection itself to dysregulate iron metabolism should not be discounted. Systemic inflammation is known to alter Fe sequestration, and while this interaction is complex, it may have also contributed to the observed serum levels.

Blood mineralogy indicated no change throughout the study; therefore, it would seem that the oral drench mineral supplementation concoction was incorrectly formulated for adolescent bison requirements. Administered at a dosage of 0.088 mL/kg, Co was given at 2 mg/kg; Cu was given at 15 mg/kg that is within the range (6.1–15 mg/mL) reported by Jackson et al (Jackson et al., 2020); Se was given at 2 mg/kg that is within the range (0.02–5 mg/mL) reported by Jackson et al (Jackson et al., 2020); finally, Zn was given at 15 mg/kg that is within the range (6.1–60 mg/mL) reported by Jackson et al (Jackson et al., 2020). The lack of an increase in serum Co, Cu, Se, or Zn following supplementation suggests potentially a failure in mineral absorption rather than an incorrect dosage. One potential mechanism for this is competitive antagonism within the gastrointestinal tract. The high concentrations of Fe and Mn measured in the drinking water may have saturated intestinal transporters, effectively blocking the uptake of supplemental Cu and Zn. Furthermore, the bioavailability of minerals in an oral drench is highly dependent on their chemical form. It is plausible that the specific formulation used had poor bioavailability in the bison digestive system, leading to its passage with minimal absorption and explaining the lack of change in blood serum concentrations.

A notable finding—independent of the supplement’s effects—was the significantly elevated serum K in animals euthanized due to M. bovis infection (Figure 3; Supplementary Table S3). Many of these individuals approached or exceeded 550 mg/mL, a threshold indicative of hyperkalemia in large ruminants (Constable, 2021). Hyperkalemia is often a terminal indicator resulting from widespread cytolysis—where dying cells release intracellular K into the bloodstream—or acute renal failure, both of which are plausible downstream effects of the body-wide infection and multiple-organ involvement characteristic of severe mycoplasmosis. While sampling is not always feasible in various management sectors, this result offers a glimpse into the underlying physiological responses of the infection’s final stages, confirming the severity of the disease process beyond simple mortality counts.

Overall, there were low parasite burden and low serological titers in this study herd; however, there were some individuals with moderate parasite burden that have contributed to their eventual mortality. Although there is no statistical significance of these independently, there may be some underlying complexities beyond the scope of this study. Future projects and future analyses may elucidate further understanding of weaned yearling bison growth phases in relation to their parasitic burden, serological health, and overall wellbeing. Relying on and applying tolerance values of circulating blood minerals from beef cattle are ill-advised. Establishing bison-specific upper and lower tolerances for blood mineralogy, blood serology, and helminth burden by age and sex classes are still needed for improved management of the species.

Ultimately, Bison and Bos genera diverged nearly 1.98 million years ago (Hassanin et al., 2013), likely resulting in the mineral requirement discrepancies noted in this study. Due to the lack of readily available supplements year-round in this area, bison may be more efficient at retaining and regulating various minerals when compared to beef cattle. As such, a supplement formulated for beef cattle could potentially be stored in various tissues in bison for later use at levels that would cause concern based on current knowledge. Further research on non-supplemented and non-immunocompromised animals of various age and sex classes may elucidate normal mineral levels in bison.

Administration of the oral drench as a treatment for several hypotheses proved unsuccessful at abating mortality/morbidity with Mycoplasma bovis, nor improved growth rates, nor increased blood mineral concentrations, nor improved disease prevalence measured with serology, nor improved gastrointestinal nematode burden or diversity (Supplementary Tables S1, S4). Use of this specific formulation of mineral supplementation in an oral drench is not recommended for treating the above morbidities.

Data availability statement

The datasets generated and analyzed for this study can be accessed from the Turner Institute for Ecoagriculture. Requests to access the datasets should be directed to Carter Kruse, Y2FydGVyLmtydXNlQHJldHJhbmNoZXMuY29t.

Ethics statement

Animals in this study remained under ownership and care of the Turner Institute of Ecoagriculture at McGinley Ranch and were under constant oversight of a permanent on-site manager working in consultation with the Turner Institute of Ecoagriculture veterinarian (coauthor TKB). This study was reviewed and approved by South Dakota State University Institutional Animal Care and Use Committee (exemption permit: 2102-013A). This study was originally intended to assess changes in blood mineral levels from supplementation and measure any effect on parasites or titer serology as a proxy for immune response. However, during this supplement trial, an unexpected outbreak of Mycoplasma bovis naturally occurred. At the time of this study, the disease of M. bovis had no known efficacious vaccine nor therapeutic treatment for bison. Unfortunately, severe morbidity and mortality accompanied this outbreak; some individuals died unexpectedly. As is standard management practice for the Turner Institute of Ecoagriculture at McGinley Ranch, some individuals with severe symptoms were removed from the study and immediately euthanized (not by the authors) according to AVMA, 2020 guidelines on page 67 under the “Euthanasia of Bison” section, and animals showing mild symptoms of M. bovis were immediately removed from the study. All those that died or were removed from the study are included as a mortality count and are depicted as an “×” in all figures to illustrate their removal from the study. Written informed consent was obtained from the owners for the participation of their animals in this study.

Author contributions

JMM: Conceptualization, Data curation, Formal Analysis, Funding acquisition, Investigation, Methodology, Project administration, Visualization, Writing – original draft, Writing – review & editing, Supervision, Resources, Validation. CGK: Conceptualization, Funding acquisition, Methodology, Resources, Writing – review & editing. TKB: Conceptualization, Methodology, Project administration, Resources, Supervision, Writing – review & editing. PMU: Formal Analysis, Investigation, Validation, Writing – original draft, Writing – review & editing.

Funding

The author(s) declared that financial support was received for this work and/or its publication. JMM was supported in part by the USDA–NIFA Hatch project award no. 1026173 and the USDA–NIFA Multistate project award no. 7004803.

Acknowledgments

The authors thank A. Pillatzki and the Animal Disease Research and Diagnostic Laboratory at South Dakota State University and the personnel at Turner Institute of Ecoagriculture and McGinley Ranch that assisted with executing this study; their respective contributions are invaluable. The Center of Excellence for Bison Studies at South Dakota State University provided logistical support for JMM. Animals for this study were owned by the Turner Institute of Ecoagriculture.

Conflict of interest

The authors declared that this work was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

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The author(s) declared that generative AI was not used in the creation of this manuscript.

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Supplementary material

The Supplementary Material for this article can be found online at: https://www.frontiersin.org/articles/10.3389/fcosc.2025.1689030/full#supplementary-material

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