Ruminants

This study aimed to evaluate the microbiological quality of colostrum on three dairy farms with different colostrum management hygiene practices and to compare it with the current colostrum quality guidelines. On farm A, colostrum was fed raw, while on farms B and C it was heat treated. On farms A and B, the feeding equipment was cleaned manually, while on farm C, an automated cleaning system was used. Samples were collected from the calf-feeding equipment and submitted for microbial culture: total plate count (TPC); total coliform count (TCC); and E. coli, enterobacteria (ENTB), staphylococci (STAP), and lactic acid bacteria counts. In addition, pH, water activity (a_W), and Brix were analyzed. Colostrum quality was defined as follows: good quality (GQ)—TPC < 100,000, TCC < 10,000, STAP < 50,000 cfu/mL, and Brix ≥ 22%; excellent quality (EQ)—TPC < 20,000, TCC < 100, STAP < 5000 cfu/mL, and Brix ≥ 25%. Mean concentrations were as follows: TPC was 3.99 × 10⁵ cfu/mL (min: 40.00, max: 1.32 × 10⁷ cfu/mL); TCC was 1.17 × 10⁴ cfu/mL (min: <detection limit, max: 6.37 × 10⁵ cfu/mL); and STAP was 1.77 × 10⁴ cfu/mL (min: <detection limit, max: 3.50 × 10⁵ cfu/mL). Approximately 54% (GQ) and 32% (EQ) of samples met the defined criteria. Farm C consistently showed lower microbial counts across all culture types. Colostrum from farm B had lower TCC, LAB, and E. coli counts than farm A but not TPC, STAP, and ENTB. These results showed that a considerable proportion of calves were fed colostrum with suboptimal quality, especially when less rigorous hygiene practices were implemented. Full article

Understanding the genetic and phenotypic basis of economically important traits is essential for designing effective breeding programs in livestock. This study aimed to evaluate the phenotypic performance and estimate genetic parameters for one reproductive trait—litter size at birth (LSB)—and three pre-weaning growth traits—birth weight (BW), weaning weight (WW), and average daily gain (ADG)—in a population of 1888 Zaraibi kids born between 2018 and 2023. Genetic parameters were estimated using animal models implemented in the MTDFREML software. The overall least squares means (±standard error) for LSB, BW, WW, and ADG were 2.22 ± 0.02, 2.03 ± 0.01 kg, 10.22 ± 0.05 kg, and 90.00 ± 0.50 g/day, respectively. Statistical analyses indicated that month of birth, year of birth, and type of birth had significant (p < 0.05) effects on all traits, while the sex of the kids had no significant effect (p > 0.05) on LSB. Direct heritability estimates (h²_d) derived from Model 1 (including additive genetic, permanent environmental, and residual effects) were 0.13 ± 0.01 for LSB, 0.30 ± 0.04 for BW, 0.38 ± 0.01 for WW, and 0.30 ± 0.10 for ADG. Under Model 2 (which incorporated maternal genetic effects and their covariance with direct genetic effects), maternal heritability (h²_m) estimates for LSB, BW, WW, and ADG were 0.05 ± 0.01, 0.15 ± 0.01, 0.12 ± 0.01, and 0.14 ± 0.01, respectively. Overall, the results emphasize the importance of maternal genetic effects in influencing pre-weaning growth traits. Therefore, maternal genetic components should be explicitly considered in genetic evaluation and selection strategies aimed at improving early growth performance in Zaraibi goats. Full article

The conservation of local breeds plays a strategic role in maintaining genetic variability, ensuring adaptive responses to environmental challenges, and preserving the cultural and socioeconomic structures of traditional communities. In this context, this study explores the potential disappearance of traditional knowledge about local breeds from an ethnozootechnical perspective. The objectives were (I) to establish the breeding history of goat and sheep breeds/ecotypes in the semi-arid region of Paraíba; (II) to estimate the diversity index; and (III) to evaluate the selection criteria used by local communities in four territories: Coletivo, Borborema, Folia, and Casaco. The study aims to support genetic conservation and improvement programs. Data collection was participatory, involving breeders from all territories. To recover the breeds’ history, questionnaires were applied to the oldest breeders, called the “guardians.” Two workshops were held to assess the diversity of breeds in the past landscape (PP) and current landscape (PA), using the Recall technique. Responses were recorded in spreadsheets for analysis. Descriptive statistics and multiple correspondence analysis (MCA) were used to assess animal distribution. The Shannon index indicated a drop in goat breed diversity, from 1.3 (PP) to 0.87 (PA). For sheep breeds, it decreased slightly from 0.7 to 0.66. Breeders reported valuing traits such as adaptability, disease resistance, fertility, and conformation. Their strong emotional connection with the animals highlights the breeds’ cultural relevance. A strong connection was found between the loss of genetic material in the studied territories and the extinction of local communities’ knowledge about local breeds. Full article

Cytokine and Anti-Müllerian Hormone (AMH) profiling were performed in prepubertal Murrah buffalo heifers’ post-progesterone supplementation and Co-synchronization (Co-synch) protocol. Cytokine (IFNγ, IL6, IL1, IL13, TNFα, and TGFβ), AMH, progesterone, and estrogen hormone estimations were conducted. The ovarian follicular pattern and fertility outcome were recorded. Eighteen prepubertal heifers, 15–17 months of age, 250–300 kg body weight (BWt) were randomly divided into three groups, Group 1: n = 6, supplemented with altrenogest 0.044 mg/kg BWt/day/heifer orally for 14 days along with Co-synch program; Group 2: n = 6, implanted Controlled Internal Drug Release (CIDR) for 14 days and co-synch program, Group 3: n = 6, received Co-synch program. Ultrasonography was performed to determine ovarian follicle status on respective days of sampling. Pregnancy diagnosis was performed around 45 and 60 days post artificial insemination (AI). The Estradiol 17-β level remained constant in Group 1, Group 2, and Group 3 during the progesterone treatment and Co-synch treatment. Estradiol levels during Co-synch were significantly less (p = 0.024) on day 9 of Co-synch (14.41 ± 1.97 pg/mL) than on day 0 (20.11 ± 0.36 pg/mL) and on day 7 (19.77 ± 0.34 pg/mL) in prepubertal buffalo heifers in Group 1. However, no significance was observed in other groups. Progesterone levels in buffalo heifers subjected to synchronization protocols varied significantly (p < 0.05) on day 7 of progesterone (P4) treatment between Group 1, Group 2, and Group 3. Supplementation of altrenogest showed a significant (p = 0.043) increase in progesterone levels by day 14 of altrenogest treatment. Progesterone varied significantly in all groups on day 9 of Co-synch protocol [Group 1 (p = 0.020), Group 2 (p = 0.041), and Group 3 (p = 0.007)]. Cytokine IFNγ showed high correlation with progesterone, indicating the role of IFNγ in puberty in buffalo heifers (r = 0.626, p < 0.01). Anti-Müllerian Hormone had a significant positive correlation when supplemented with altrenogest with IFNγ (r = 0.673, p < 0.01) and TGFβ (r = 0.463, p < 0.01), whereas it was a negatively correlated with TNFα (r = −0.34, p < 0.05). Based on Karl Pearson correlation coefficients, IL13 and TGFβ could be considered as markers for puberty in buffalo heifers. Full article

The objective of this study was to evaluate whether the addition of fibrolytic enzymes to the diet of cattle in confinement improves feed digestibility weight gain; as well as evaluating the profile of fatty acids in the ruminal environment and in meat fatty acids profile. In total, 24 male dairy cattle (Holstein) aged 8 months and weighing an average of 212 kg, were divided into 2 groups: control (without additive) and treatment (0.25 g of enzymes/kg of dry matter of total diet). The experiment lasted 120 days. The first 20 days are allocated for the adaptation period. During the study, samples of blood, ruminal fluid, and feces were collected, as well as weighing the cattle and measuring their daily feed consumption. There was no effect of treatment on body weight, feed intake, feed efficiency, and nutrient digestibility (p > 0.05). Cholesterol levels were higher in the serum of cattle that consumed the enzyme; serum amylase activity was higher in cattle that received the additive only on day 120 of the experiment (p < 0.05). There was a greater amount of volatile fatty acids in the ruminal fluid, combined with a greater amount of acetic acid. The amount of fat in the meat of cattle that consumed fibrolytic enzymes was higher compared to the control group (p < 0.05). Meat from cattle in the treatment group had lower amounts of saturated fatty acids and higher amounts of unsaturated fatty acids (p < 0.05). The fibrolytic enzymes addition altered rumen fermentation in such a way that lipid metabolism was changed, which had a serious impact on cholesterol and tissue levels, that is, in the meat that had a greater amount of total lipids, an unsaturated fat. Full article

This study evaluated the effects of organic trace mineral supplementation on growth performance, antioxidant indices, mineral status, and diarrhea incidence in dairy calves raised in arid climates. Twenty-five male Holstein calves were randomly assigned to five dietary treatments for 21 days, as follows: (1) control group (no organic mineral supplementation), (2) copper-methionine (Cu-Met) supplemented diet, (3) zinc-methionine (Zn-Met) supplemented diet, (4) manganese-methionine (Mn-Met) supplemented diet, and (5) Zn-Met + Cu-Met + and Mn-Met in a premix supplemented diet. Mineral supplementation had no effect on final body weight or average daily gain. However, the concentrations of Zn, Cu, and Mn significantly increased (p < 0.01) in blood and feces of treated animals. The highest blood concentrations of Zn and Mn were observed in calves receiving Zn-Met, while Mn-Met supplementation significantly influenced blood Cu levels. The highest Zn excretion was recorded in calves receiving the organic mineral premix, whereas the highest Mn and Cu excretion was observed in the Cu-Met group. Additionally, mineral supplementation enhanced total antioxidant capacity and superoxide dismutase activity in plasma samples (p < 0.01). These findings suggest that organic mineral supplementation could be an effective strategy to improve mineral bioavailability and support the health of dairy calves during early life in arid climates. Full article

Virtual fencing (VF) technology represents an innovative approach to livestock management, utilizing GPS-enabled collars to establish invisible boundaries through auditory and mild electrical stimuli. While VF offers potential benefits such as enhanced pasture management flexibility and reduced labor costs, its widespread adoption faces challenges including high initial investment costs, connectivity issues, GPS accuracy limitations, potential device durability concerns, and individual animal variability in learning and response. Furthermore, despite studies showing rapid learning and generally minimal long-term welfare impacts, questions remain regarding optimizing training protocols, addressing occasional short-term behavioral disruptions and collar abrasions, assessing long-term welfare effects across diverse systems (especially intensive and dairy), and improving scalability. To comprehensively assess the potential and limitations of this technology and guide its future development and implementation, a review integrating existing knowledge on the efficacy, welfare implications, and practical applications of VF in cattle production systems is essential. This review examines the efficacy, welfare implications, and practical applications of VF in cattle production systems. Studies demonstrate that cattle rapidly learn to associate auditory cues with electrical pulses, achieving high containment rates (≥90%) within days, with minimal long-term welfare impacts as indicated by stable cortisol levels. However, short-term behavioral disruptions and occasional collar-related abrasions have been reported, particularly in dairy cattle. While VF enhances pasture management flexibility and reduces labor costs, challenges such as connectivity issues, individual animal variability, and high initial investment costs limit its widespread adoption. The findings suggest that VF is a promising tool for precision livestock farming, though further research is needed to optimize training protocols, assess long-term welfare effects, and improve scalability across diverse farming systems. Full article

Leonardite (LEO), a microbial derived product rich in humic and fulvic acids, has been tested, due to its beneficial properties for health and well-being, as a feed additive, mainly in non-ruminant species. Although there are some reports of LEO supplementation in ruminants fed with high-to medium-forage based diets, there is no information available of the potential effects of LEO in ruminants fed, under sub-tropical climate conditions, with high-energy diets during long-term fattening. For this reason, the objective of the present experiment was to evaluate the effects of LEO levels inclusion in diets for feedlot lambs finished over a long-term period. For this reason, 48 Pelibuey × Katahdin lambs (initial weight = 20.09 ± 3.55 kg) were fed with a high-energy diet (88:12 concentrate to forage ratio) supplemented with LEO (with a minimum of 75% total humic acids) for 130 days as follows: (1) diet without LEO, (2) diet supplemented with 0.20% LEO, (3) diet supplemented with 0.40% LEO, and (4) diet supplemented with 0.60% LEO. For each treatment, Leonardite was incorporated with the mineral premix. Lambs were blocked by weight and housed in 24 pens (2 lambs/pen). Treatment effects were contrasted by orthogonal polynomials. The average climatic conditions that occurred during the experimental period were 31.6 ± 2.4 °C ambient temperature and 42.2 ± 8.1% relative humidity (RH). Those values of ambient temperature and RH represent a temperature humidity index (THI) of 79.07; thus, lambs were finished under high heat load conditions. The inclusion of LEO in diet did not affect dry matter intake (p ≥ 0.25) and average daily gain (p ≥ 0.21); therefore, feed to gain ratio was not affected (p ≥ 0.18). The observed to expected dietary net energy averaged 0.96 and was not affected by LEO inclusion (p ≥ 0.26). The lower efficiency (−4%) of dietary energy utilization is an expected response given the climatic conditions of high ambient heat load presented during fattening. Lambs that were slaughtered at an average weight of 49.15 ± 6.00 kg did not show differences on the variables measured for carcass traits (p ≥ 0.16), shoulder tissue composition (p ≥ 0.59), nor in visceral mass (p ≥ 0.46) by inclusion of LEO. Under the climatic conditions in which this experiment was carried out, LEO supplementation up to 0.60% in diet (equivalent to 0.45% of humic substances) did not did not help to alleviate the extra-energy expenditure used to dissipate the excessive heat and did not change the gained tissue composition of the lambs that were fed with high-energy diets during long-term period under sub-tropical climate conditions. Full article

In 2020, the European Union endorsed its “Farm-to-Fork” strategy, emphasizing the need for transparency in the food production chain and communication of the sustainability level and nutritional value of food products to the consumer through labeling. For animal-based products, this also includes information about the husbandry systems under which the animals are raised. At the same time, people are becoming increasingly concerned both as citizens and as consumers about animal welfare issues in production species, as animal welfare is considered an integral part of sustainability and food security. This has led to the development of various enhanced animal welfare labeling schemes, initiated by public or private entities, or even as a partnership of both. Specifically for cattle, sheep, and goats, various standards have been developed and implemented in Europe, all establishing higher welfare standards compared to conventional farming, and in some cases exceeding the minimum requirements for organic farming as set by Regulation (EU) 2018/848. Most of these standards, especially those developed by NGOs advocating for animal welfare or through public initiative, were developed for semi-intensive to extensive systems. They primarily incorporate animal-based measures, including positive welfare indicators, offering a holistic approach to animal welfare evaluation. Although there is significant heterogeneity in European animal welfare standards, nearly all of them promote access to pasture, comfort, environmental enrichment, and, in some cases, even mother–young bonding. Full article

Fetal programming suggests that maternal nutrition during gestation influences offspring growth, development, and productivity. This study evaluated the effects of prenatal protein-energy supplementation on the lifetime performance of Nellore cattle. Twenty-eight nulliparous heifers were inseminated and assigned to one of two groups: Non-Programmed; receiving only mineral supplementation; or Fetal Programmed (FP); receiving additional protein-energy supplementation throughout gestation. Cows in the FP group maintained significantly better body condition score during gestation (p < 0.01), and their calves exhibited greater body weight (BW) during the first 56 days (p < 0.05) and a tendency to grow to a greater BW up to 250 days (p < 0.10) in addition to improved morphological traits, such as increased rump width and length at 45 days of age (p ≤ 0.02). However, these advantages were not sustained in later growth stages, as no significant differences were observed in final body weight, ultrasound carcass traits, or overall feedlot performance. These findings suggest that while prenatal nutrition can influence early developmental traits, its long-term impact on offspring performance may be limited under consistent postnatal management. Nonetheless, the limited sample size, combined with the absence of molecular data and individual feed intake and efficiency measurements, constrains a more comprehensive interpretation of the programming effects on offspring performance. Further research is needed to explore the molecular mechanisms of fetal programming, particularly its epigenetic effects and interactions with postnatal nutrition, to optimize strategies for improving the efficiency and sustainability of beef cattle. Full article

Enteric methane emissions from ruminants substantially contribute to global greenhouse gas emissions, necessitating effective mitigation strategies that also support animal productivity. This study assessed the efficacy of a multi-component feed additive that combines medium-chain fatty acids (MCFAs), live yeast, plant-based agents, and Vitamin B, in reducing methane emissions, improving feed efficiency, and enhancing growth and immune function in sheep. Twenty crossbred castrated male sheep (52 ± 3.7 kg) were divided into control and treatment groups (n = 10 each), with the treatment group receiving grass pellets supplemented with the multi-component feed additive (20 g/day) for 71 days, including a 30-day acclimatisation period. Feed intake, methane emissions, growth performance, and blood parameters were monitored using BioControl pens, GreenFeed units, and haematological analyses. The treatment group exhibited a 24% increase in daily feed intake (p < 0.001) and a 22.2% reduction in methane yield per kg of dry matter ingested (p < 0.001), which could be attributed to MCFAs’ anti-methanogenic properties and yeast’s rumen modulation. However, no significant improvements were observed in daily live weight gain, feed conversion efficiency, or immune parameters, suggesting limited energy utilisation for growth. These findings highlight this novel multi-component feed additive as a promising strategy for methane mitigation in forage-based systems. Further dosage optimisation and dietary integration could enhance its application across ruminant species, contributing to sustainable livestock production. Full article

Data for growth (birth, weaning and yearling weights) and carcass (longissimus muscle area, intramuscular fat percentage and depth of rib fat) traits and 50K SNP marker data to calculate the genomic relationship matrix were collected from 738 Brangus heifers. Univariate and multivariate genomic best linear unbiased prediction models based on the genomic relationship matrix and univariate and multivariate artificial neural networks models with 1 to 10 neurons, as well as the learning algorithms of Bayesian Regularization, Levenberg–Marquardt and Scaled Conjugate Gradient and transfer function combinations of tangent sigmoid–linear and linear–linear in the hidden-output layers, including the inputs from genomic relationship matrix, were created and applied for the analysis of growth and carcass data. Pearson’s correlation coefficients were used to evaluate the predictive performances of univariate and multivariate genomic best linear unbiased prediction and artificial neural networks models. The overall predictive abilities of genomic best linear unbiased prediction and artificial neural network models were low in the univariate and multivariate analysis. However, the predictive performances of models in the univariate analysis were significantly higher than those from models in the multivariate analysis. In the univariate analysis, models with Bayesian Regularization and the tangent sigmoid–linear or linear–linear transfer function combination yielded higher predictive performances than models with learning algorithms and genomic best linear unbiased prediction models. In addition, predictive performances of models with tangent sigmoid–linear transfer functions were better than those with linear–linear transfer functions in the univariate analysis. Full article

The aim of this study is to review the supplementation of polyphenol on milk composition and milk fatty acid content in dairy animal. A systematic review of literature was carried out by using Google Scholar, Scopus, and Science Direct databases. The PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines methodology was carried out and as a result, 21 articles were included. Results showed that polyphenol supplementation significantly affect milk saturated fatty acid content (p < 0.00001) and milk medium-chain fatty acid content (p < 0.0001). Meanwhile, polyphenol supplementation effects significantly in the subgroup of agro-industrial by-products (p < 0.05) for milk protein content, grain (p < 0.05) for milk lactose content, all the subgroup for milk saturated fatty acid content and both grain and agro-industrial by-products for milk medium-chain fatty acid content. In conclusion, milk saturated fatty acid is affected by polyphenol supplementation regardless of polyphenol sources. However, it is recommended to include more studies in future to obtained a higher heterogeneity. Full article

The estimation of body chemical composition is necessary to determine the nutrient requirements of growing/finishing cattle, but recent analyses indicate that published equations provide erroneous results when applied to diverse breed types and sexes. The objective of this analysis was to develop equations to estimate empty body and carcass chemical composition for different breed types and sexes. A dataset was developed from the published literature that contained 359 treatment means from 46 studies published between 1971 and 2021. Stepwise regression was used to develop prediction equations using Akaike’s Information Criteria to estimate empty body and carcass fat, protein, and ash concentrations (%). Empty body fat, protein, and ash could be predicted from combinations of empty body water, empty body fat, and empty body protein (RMSE = 1.53, 1.85, and 0.67; R² = 0.99, 0.98, and 0.95). Breed type and sex affected the intercept and (or) slope coefficients to predict empty body fat, protein, and ash. Carcass fat, protein, and ash could be predicted from combinations of carcass water, carcass fat, and carcass protein (RMSE = 1.77, 1.62, and 0.82; R² = 0.97, 0.98, and 0.93). Breed type and sex affected the intercept and (or) slope coefficients to predict protein and ash, but not fat. Equations adjusted for breed type and sex may be more robust than previously published equations based on a single breed or sex. Full article

The phalanges of Karagouniko ewes and Hellenic goats were the subject of the present quantitative study, with the objective of determining whether any differences existed on the corresponding bones of the different digits. The lengths of the phalanges of the third and fourth digits of the fore and hind autopodia, the smallest diaphyseal breadths of the first and second phalanges, the breadths of the proximal and distal ends of the first and second phalanges, the lengths of the dorsal surfaces of the third phalanx, and the heights of the extensor processes of the third phalanx were measured. A total of 44 linear measurements were recorded for each animal species. The summation of the lengths of the digital bones revealed that the third frontal digit was longer than the fourth frontal digit in both animal species and the fourth hind digit was longer than the third hind digit in both animal species. Furthermore, the lengths of the third and fourth frontal digits were greater than those of the corresponding hind digits in both species. The findings of the current metric analysis suggest that the lengths of the paired digits differ in sheep and goat. The results indicate that the morphometry of the digital bones could be important from phylogenetic, biomechanical, and clinical aspects. Full article

Contamination by multi-mycotoxins in cattle feed can lead to increased susceptibility to diseases and loss of performance. The present study aimed to investigate the occurrence of multiple mycotoxins present in the diet of beef cattle feedlots in Brazil. Chromatographic analyses were performed on 152 TMR samples from seven states, representing the diet provided to 1,246,522 animals. Contamination by mycotoxins was found in 100% of the TMR samples analyzed, with the most frequent being fumonisins, present in 100% of the samples, followed by zearalenone, which contaminated 79.6% of the samples, and subsequently by aflatoxins, deoxynivalenol, and T-2, while HT-2 was not detected in any of the samples. Furthermore, 2.6% of samples showed co-occurrence of five different types of mycotoxins, 23.7% presented four mycotoxins, 41.4% three mycotoxins, 22.4% two mycotoxins, and 9.9% of the samples showed contamination by only one mycotoxin. The significant prevalence of mycotoxins of the Fusarium and Aspergillus genera in the samples of the present study indicates a notable degree of pre- and post-harvest contamination in these beef cattle diets. Further studies are needed to define methods for monitoring cattle exposure to clarify its effects, even at low levels, and reduce the impacts on beef cattle production in Brazil. Full article

The purpose of this study was to evaluate the effects of short- and long-distance road transport and temperament on β-endorphin (β-EP) concentrations in 23 Limousine bulls, aged 12 ± 2 months old, taking into account the related effect on body weight (BW) decrease. Animals were transported by road from France to Sicily over a distance of 2200 km in about 33 h. Bulls were divided into calm and reactive subjects based on their exit velocity (EV) measurements taken one week prior to transportation. Blood samples were taken during four different time points: in the morning, immediately before loading in baseline conditions; after the short-distance road transport of 55 km; at their arrival in Sicily after a long-distance road transport of 2200 km; and after 15 days of stabling in finishing and fattening barns, before slaughtering. Animals were weighed before departure, at the arrival in Sicily, and after 15 days. Significant effects of time, temperament, and their interaction were observed for β-EP. It increased after long-distance transport in both groups, but more markedly in calmer bulls, returning to baseline values after 15 days. Significant effects of time were also observed for BW, which decreased after long-distance road transport and restored after 15 days in both groups. The results suggest that long-distance road transport induces a significant increase in the β-endorphin concentrations in Limousine bulls, with the greatest increase in calm subjects. Full article

The emerging field of study of blood microbiota reveals the presence of bacteria in the blood of healthy animals. In endangered species such as the American bison (Bison bison), the analysis of this microbiota is crucial for conservation, as changes in these communities or the development of pathogens may affect their health and compromise herd viability. Here, we analyzed and compared the bacterial blood microbiota of healthy adult and juvenile bison in Mexico (Janos, Chihuahua), identifying those bacterial taxa with potential pathogenicity for these individuals. Blood samples were collected from 12 juvenile and 12 adult bison. The V3–V4 region of the 16S rRNA gene was amplified, and next-generation sequencing was subsequently performed on the Illumina NovaSeq platform. The bacterial taxa observed in the blood of these individuals (Firmicutes, Proteobacteria, Bacteroidota, Actinobacteria, Fusobacteriaceae, Lachnospiraceae, Oscillospiraceae, and Ruminococcaceae) have been previously reported to be abundant in the rumen and feces of bison. The most notable difference was observed for Mycoplasma wenyonii, which was significantly enriched in juveniles compared with adults. New sequencing technologies can be practically applied to improve the management and conservation of vulnerable species such as the American bison. Full article