Ruminants, Volume 5, Issue 4 (December 2025) – 19 articles

Edible trees, such as Bordão-de-velho (BVP; Samanea tubulosa), are being studied for their nutritional potential and the presence of bioactive compounds that influence ruminal fermentation. This study aimed to evaluate, using an in vitro assay, the effects of increasing the inclusion of BVP pods in dairy cow diets formulated with different energy levels. The experiment was conducted with eight treatments obtained from a 4 × 2 factorial arrangement, containing four levels of pod inclusion (0, 100, 200, and 300 g/kg dry matter) and two dietary energy levels (high and low). Increasing BVP levels resulted in a linear reduction in gas production from digestible organic matter in low-energy diets, without altering dry matter and organic matter digestibility or methane production. There was an increase in pH and in the acetate/propionate ratio, along with a reduction in the concentrations of short-chain fatty acids and isoacids. In conclusion, Samanea tubulosa pods improve fermentation efficiency and reduce gas production, making them a promising forage source for low-productivity animal diets. Full article

This narrative review aims to summarize, synthesize, and organize current knowledge on the adaptation of sheep and goats to stressful environments and to discuss how these adaptations contribute to food security in vulnerable communities. A structured search of Web of Science, Scopus, PubMed, and Google Scholar was conducted using combinations of terms related to sheep and goats, harsh environments (e.g., arid and semi-arid regions, heat stress, water restriction, poor-quality forage), and adaptation or resilience, combined with Boolean operators. A total of 1718 research publications were found, of which 86 were retained as the most relevant because they provided direct and detailed evidence on anatomical, physiological, digestive–microbiome, behavioral, and genomic adaptations of sheep and goats to stressful environments. The selected studies describe a wide range of phenotypic and integumentary traits, thermoregulatory and endocrine responses, digestive and microbial adjustments, behavioral strategies, and genomic signatures that, together, allow small ruminants to maintain basic functions, reproduction, and production under conditions of climatic and nutritional stress. Evidence from these studies also highlights how adaptive traits support herd productivity, economic stability of households, and the sustainable use of natural resources in regions where climatic variability and resource scarcity are common. Overall, the synthesis presented here underscores the importance of conserving and strategically using locally adapted sheep and goat breeds, incorporating resilience-related traits into breeding and management programs, and prioritizing further research on genomic, microbiome, and epigenetic mechanisms that underpin adaptation to harsh environments. Full article

The aim of this study was to evaluate the relationship between cows’ hepatic lipid content (HLC) at 10 days in milk (DIM) and their metabolic status, health, and production during transition and early lactation periods. HLC was determined in 103 cows from a grazing Chilean dairy herd via cytologic examination of the liver through fine needle biopsies, categorized as mild, moderate, or severe. Blood metabolites were evaluated in the transition period, together with diseases in the postpartum period and milk production during the first 90 DIM. In pre-partum and postpartum periods, primiparous cows with severe HLC showed higher plasma cholesterol than multiparous cows with mild HLC. Postpartum, cows with severe HLC had higher serum non-esterified fatty acids (NEFAs) and NEFA/cholesterol ratios than those with mild HLC. Similarly, cows with moderate and severe HLC presented higher plasma β-hydroxybutyrate and greater risk of subclinical ketosis than cows with mild HLC. Additionally, cows with severe HLC had higher milk production and lower milk protein content than those with mild HLC. These results indicate that moderate to severe HLC at 10 DIM was associated with negative energy balance and subclinical ketosis, whereas severe HLC was associated with increased milk production and decreased milk protein content. Full article

The present study aimed to apply machine learning algorithms to estimate respiratory rate (RR, breaths min⁻¹) and rectal temperature (RT, °C) as indicators of thermal stress in Dorper breeding rams, based on environmental and thermal variables obtained through infrared thermography. The algorithms Random Forest (RF) and Support Vector Regression (SVR) with radial kernel were employed, using ocular globe temperature (OGT), air temperature (AT), relative humidity (RH), and coat surface temperature (CST) as predictor variables, and rectal temperature (RT) and respiratory rate (RR) as response variables. Data were collected on a property located in Garanhuns, Pernambuco State, Brazil, under two environmental conditions (with and without climate control), totaling 20 monitored animals and 120 paired observations. Model performance was evaluated using the coefficient of determination (R²), Root Mean Squared Error (RMSE), and Mean Absolute Error (MAE), complemented by cross-validation (k-fold = 10), and model interpretability was assessed using SHapley Additive exPlanations (SHAP) to quantify the contribution of each predictor variable to model predictions. The results indicated that the RF model showed superior performance in predicting the physiological variables RR and RT, with higher coefficients (RR: R² = 0.858; RT: R² = 0.687) and lower error values. For RR, the RF model achieved RMSE = 16.38 and MAE = 13.33; while for RT, the errors were RMSE = 0.217 and MAE = 0.154. In contrast, the radial kernel SVR model showed lower performance, with R² values of 0.742 (RR) and 0.533 (RT), and RMSE and MAE values of 21.05 and 17.38 for RR, and 0.262 and 0.196 for RT, respectively. The application of machine learning-based models proved to be a viable and accurate alternative for estimating physiological indicators of thermal stress, contributing to the development of automated thermal management strategies for sheep in the Brazilian semi-arid region. The proposed data-driven approach demonstrates that low-cost thermal sensors combined with explainable artificial intelligence can support automatic decision-making for climate adaptation and animal welfare in semi-arid sheep production systems. Full article

Background: Cortisol is known as the main hormone released during stress responses in cattle and has been used to assess various stressors, including heat stress. This study investigated hair cortisol concentration (HCC) in different hair coat colors in dairy cows under natural heat stress conditions (temperature humidity index = 75). Methods: Hair samples were collected from the forehead region of ten multiparous cows (Brown Swiss, Montbéliarde, and Holstein) per group color at both the beginning and end of a three-week peak summer period in 2024 in the region of Jendouba, North Tunisia. Cows were grouped according to hair coat color (black, brown, red, white, and yellow) for subsequent analysis. Hair samples were prepared using a methanol-based separation protocol and analyzed via enzyme-linked immunosorbent assay (ELISA). Results: Meteorological data confirmed that cows were sustained under heat stress, with an average temperature humidity index value of 75; results indicated that black hair had considerably more HCC than white hair (p < 0.05). The results showed that there is a significant difference between HCC under three clusters (p < 0.05) according to hair color. Conclusions: The study emphasizes that hair color, along with factors such as breed and environmental conditions, should be carefully considered when using HCC to assess stress in cattle beyond simply black or white hair color. Full article

Studies in taurine breeds have shown that genetic selection can improve the fatty acid (FA) profile of bovine milk, but studies are scarce considering Zebu animals. In this study, genetic parameters for FA concentrations and unsaturation indexes in the milk fat of Zebu cows were estimated, with emphasis on Gir and Guzerá breeds. Milk samples from 299 Gir and 266 Guzerá cows belonging to 22 herds distributed throughout Brazil were analyzed using gas chromatography. Fourteen individual FAs, 11 FA groups, four nutritional indexes, and five unsaturation indexes were evaluated. Tri-trait Bayesian models were applied, including 305-day milk and fat yields as “anchor” traits. Systematic effects such as contemporary group, age at calving, diet, sampling age class, and days in milk were considered. Palmitic acid was the most abundant FA, followed by oleic, stearic, and myristic acids. Heritability estimates ranged from moderate to high: 0.28–0.66 in Gir cows, and 0.25–0.74 in Guzerá cows, for individual FAs and FA groups. Unsaturation indexes also showed moderate to high heritability. Genetic correlations were generally strong, with long-chain FAs negatively correlated with short- and medium-chain FAs. The results suggest that genetic selection can be applied to improve the nutritional profile of milk fat in Zebu cattle. Full article

Climate change poses significant challenges to livestock, particularly in tropical regions. The Amazon biome, which hosts one of the world’s largest cattle populations, faces growing risks of nutritional, metabolic, and infectious diseases driven by heat stress (HS) and environmental instability. This systematic review synthesizes evidence from primary studies, international reports (IPCC, FAO), and peer-reviewed literature on cattle physiology, disease dynamics, and climate adaptation. HS reduces feed intake, disrupts endocrine–metabolic homeostasis, and suppresses immunity, increasing susceptibility to metabolic, deficiency and infectious diseases. Breed-specific immune responses offer opportunities for genetic and management-based adaptation. Socio-economic impacts disproportionately affect smallholders, linking livestock health to food security and poverty. Ensuring sustainable cattle production in the Amazon will require climate-smart strategies integrating nutrition, genetics, reproduction, and health management, supported by policies that align adaptation and mitigation. Future research should prioritize immune-metabolic biomarkers, periparturient disease monitoring, and genomic tools for thermotolerance. Full article

Despite the critical importance of nutritional assessment in veterinary medicine, internationally recognized guidelines for compromised ruminants remain absent. This paper addresses this significant gap by presenting comprehensive nutritional assessment protocols adapted from small animal and equine guidelines, combined with clinical experience and ruminant-specific considerations. Therefore, the objective of this article is to establish standardized nutritional assessment guidelines for compromised ruminants that facilitate early detection of risk factors and nutritional imbalances affecting animal welfare and productivity, while guiding appropriate clinical nutritional interventions. The guidelines integrate systematic screening and extended evaluation protocols encompassing patient signalment, comprehensive health interviews, environmental examination, and nutrition-focused clinical assessments. The framework incorporates validated scoring systems including body condition scoring, fecal consistency and digestibility scores, rumen fill assessment, and muscle scoring. Laboratory evaluations including blood biochemistry, hematology, milk quality records, and metabolite profiling support clinical decision-making. The proposed assessment framework addresses animal-specific factors, diet-related considerations, feeding management practices, and environmental influences on nutritional status. Critical evaluation points include alimentary system function and integrity, forestomach assessment, and detection of malabsorption syndromes. The guidelines emphasize that many nutritional abnormalities manifest non-specifically, and detection limitations exist, particularly in peracute presentations. In conclusion, successful clinical nutritional interventions require comprehensive assessment protocols that prioritize rumen health maintenance and oral diet delivery whenever possible. The guidelines we suggest will provide veterinary and nutritional practitioners with systematic tools for evaluating compromised ruminants, establishing appropriate interventions, and monitoring outcomes using SMART goals. Further research is warranted to refine specific dietary requirements for compromised ruminants and validate intervention protocols across diverse production systems. Full article

The present study determined the effects of varying inclusion levels of baobab oilseed cake (BOSC) combined with fossil shell flour (FSF) diets on body condition scores, body weight gain, and nutritionally related blood metabolites of Angora goats. Twenty-four Angora goat wethers aged 5–6 months, weighing 12.75 ± 1.5 kg, were kept in individual pens for 105 days of successive feeding, including a 14-day adaptation period. Goats were randomly allocated to four dietary treatments: 0%, 5%, 10%, and 15% BOSC (n = 6). Each goat was offered experimental diets at 4% of its body weight daily at 08:00. Goats were then released to graze on natural pastures at 10:00 and returned to their respective pens at 16:00 daily. Body weight gain, body condition scores, and blood concentrations were determined. Angora wethers BCS linearly increased (p < 0.05) as weeks progressed in all inclusion levels of BOSC. Body weight gain increased linearly (p < 0.05) in goats fed 0% and 10% BOSC across the 13-week feeding period, while goats fed 5% BOSC showed a sharp quadratic increase (p < 0.05) between weeks 5–6 and those fed 15% BOSC between weeks 3–8. Creatinine levels showed a sharp quadratic decline (p < 0.05) between 10–15% BOSC inclusion, while urea levels quadratically declined (p < 0.05) between 0–5% inclusion. Phosphorus concentrations also decreased quadratically (p < 0.05), reaching their lowest values between 5% and 10% BOSC, while total protein, glucose, magnesium, albumin, and calcium remained unchanged (p > 0.05) across dietary treatments. In conclusion, this preliminary study suggests that the inclusion of 15% BOSC improves BWG, BCS, and nutritionally associated blood metabolites in Angora goats. Further studies with a larger number of animals are recommended to confirm these findings. Full article

Oxidative stress impairs the productivity and welfare of heat-stressed hair sheep; however, the key factors contributing to its occurrence remain unclear. Twenty-two Dorper × Katahdin ewe lambs weighing 23.5 ± 2.8 kg and experiencing outdoor heat stress in a desert region were used to establish the contribution of climatic variables, physiological responses, metabolism, and feedlot performance to the oxidant-antioxidant imbalance. Pearson’s correlation, principal component analysis, and multiple linear regression were applied to the datasets. Oxidative stress biomarkers showed positive relationships with average and minimum climatic variables, morning rectal temperature, serum triglycerides and insulin, and feed efficiency. Still, these biomarkers were negatively correlated with maximum ambient temperature (Te) and temperature-humidity index (THI), morning and afternoon respiratory rate (RR), total protein, and feed intake. While total oxidant capacity and fat oxidation were mainly associated with decreased maximum Te, protein oxidation was primarily associated with increased morning RR. Total antioxidant capacity was favored by a reduction in maximum THI and oxidative stress index (OSI) by an increase in maximum relative humidity. With minimal contribution (≤6%), protein and fat oxidation were also explained by increased serum insulin and feed intake, respectively, whereas OSI was explained by increased weight gain. Overall, the presence of oxidative stress in feedlot hair sheep experiencing outdoor heat stress was regulated by a combination of climatic conditions, morning RR, and, to a lesser extent, productive performance. Full article

Spineless cactus, known for its high heat tolerance and low water requirements, offers a sustainable alternative for animal feed in regions where conventional crops struggle to thrive. This study aimed to evaluate the carcass characteristics, leg tissue composition, and non-carcass constituents of lambs fed increasing levels (0, 15, 30, and 45% based on dry matter) of spineless cactus as a replacement for Tifton hay. Additionally, we estimated body weight and carcass traits using biometric measurements (BM). Forty male lambs, with an average initial body weight of 23.6 ± 2.58 kg, were subjected to a feedlot regime. Empty body weight was the only variable that showed a significant orthogonal contrast between the control group (0%) and those fed spineless cactus (p < 0.05). A quadratic regression effect (p < 0.05) was observed for the weights of the cold half carcass, neck, shoulder, and leg cuts. No significant effects were found on non-carcass components or biometric measurements. Biometric measurements showed strong positive correlations with slaughter weight and carcass characteristics. Based on these findings, replacing 30% of Tifton hay with spineless cactus is recommended as the optimal level, as it maintains carcass quality, tissue composition, and non-carcass traits. Moreover, biometric measurements prove to be effective tools for predicting slaughter weight and carcass characteristics, offering practical value for farmers seeking efficient and sustainable production strategies. The inclusion levels of 24.25% to 27.50% of spineless cactus in the diet of confined sheep appear to be the most efficient, promoting high-value commercial cuts without compromising carcass quality parameters. These levels balance productive performance and sustainability, especially in semi-arid regions. Full article

Individual vocal recognition is essential for social cohesion and survival among conspecifics. In sheep, it facilitates postnatal identification and strengthens the mother–offspring bond. Although vocal individuality has been well-documented in lambs and ewes, little is known about whether rams—typically reared separately in farming systems—exhibit acoustic distinctiveness. This study investigated whether rams express vocal individuality across different emotional contexts and whether their calls convey contextual information. Adult rams’ vocalizations were recorded across five emotionally distinct contexts: physical and visual isolation (morning and evening), auditory exposure to ewes’ bells without visual contact, feed anticipation, and feed denial. Implementing discriminant function analyses and linear mixed models, we assessed individual distinctiveness and contextual variation in acoustic parameters. Rams exhibited vocal individuality ranging from 59% to 80%, with higher distinctiveness in negative contexts compared to positive ones. Vocal distinctiveness persisted across contexts, albeit to a lesser degree, suggesting some degree of acoustic stability. Calls were classified above chance by context, suggesting rams use vocalizations to convey affective states. Formant dispersion and amplitude variation were the most informative raw acoustic parameters under negative from positive contexts. The findings indicate that rams exhibit context-dependent vocal individuality, potentially conveying affective states through vocalizations. Full article

Improving livestock nutrition with natural supplements can enhance productivity and meat quality. This study evaluated whether a clayey micromineral compound (CMC) in lamb diets improves feed efficiency, health, and meat traits. Twenty-four 60-day-old Dorper/Santa Inês crossbred lambs (28.41 ± 4.147 kg initial weight) were randomly assigned to four CMC doses (0%, 0.4%, 0.8%, or 1.2% of dry matter intake/day) for 90 days, following a 15-day adaptation. The lambs were individually housed, with daily feed intake monitoring, weekly weight measurements, and blood analyses at the start and end. On day 89, rumen fluid was sampled for digestion analysis, and post-mortem evaluations were used to assess meat quality and rumen health. The results showed that 0.8% CMC optimized fat and fiber digestion (p < 0.05), while higher doses linearly improved meat color intensity (p < 0.05). Blood tests indicated better liver function at intermediate doses (p < 0.05). However, the CMC did not affect overall growth, feed intake, or carcass traits. The supplement was safe but provided selective benefits. These findings suggest that CMCs could enhance feed efficiency and meat appeal, although further research is needed to refine dosing for maximum impact. Full article

A significant gap in specific nutritional guidelines for ruminants with compromised health exists. Due to their unique anatomy, physiology, and metabolic processes, further research is needed to establish accurate, evidence-based recommendations tailored to these animals. This review highlights the critical role of clinical ruminant nutrition and provides provisional recommendations based on studies in other species (e.g., changes in nutrient requirements in different morbidities available for humans and less for companion animals). These suggestions should be interpreted cautiously until more definitive, species-specific data become available. The review includes the foundational principles of clinical nutrition in ruminants, with particular emphasis on the pathophysiology of nutrient utilization. It explores the roles of energy, protein, vitamins, and minerals during illness or injury and discusses how these nutrients can be strategically applied in clinical interventions. Considerations for designing diets for compromised ruminants are also addressed, considering both physiological needs and the challenges posed by illness and injury states. Practical aspects of diet delivery during treatment are examined, including the indications, benefits, limitations, and potential side effects of route of feeding. Clinical nutrition can be administered orally, enterally (including rumen delivery) or parenteral, depending on the localization of the pathology and the integrity of the alimentary tract. Nutrients should be provided based on livestock requirements and pathophysiology and severity of the primary morbidity. Oral or ruminal provision of diet should be prioritized to maintain rumen functionality. Additionally, a list of pharmaconutrients with potential clinical applications in ruminant medicine is presented to encourage future research and integration into veterinary practice. The success of clinical nutritional interventions can be measured by improvements in appetite, behavior, and health of the compromised ruminant. Full article

Urea is one of the most widely used sources of non-protein nitrogen (NPN) in ruminant diets due to its low cost and high availability. However, its rapid solubilization in the rumen can result in abrupt ammonia release, leading to toxicity risks and low nitrogen utilization efficiency. In this context, slow-release technologies, particularly microencapsulation, have been developed to synchronize NPN release with fermentable carbohydrate availability, thereby enhancing microbial protein synthesis, improving animal performance, and reducing environmental impacts. This review compiles recent advances in urea microencapsulation, emphasizing different wall materials such as waxes, lipids, polysaccharides, and fatty acids, as well as drying techniques and formulation strategies. Slow-release urea (SRU) addition in small ruminants’ diet may increase nutrient intake and digestibility, improve N balance, and reduce urinary excretion losses. Regarding performance, positive responses are observed when nitrogen release is properly synchronized with energy availability, although the results may vary depending on the encapsulant type, forage-to-concentrate ratio, and ruminal passage rate. Additionally, effects on meat quality and environmental parameters indicate that this technology holds not only zootechnical but also socio-environmental potential. It is concluded that urea microencapsulation can represent a promising alternative to optimize NPN use efficiency in ruminant production systems, though greater methodological standardization, long-term evaluations, and comparative economic analyses are required to encourage its broader adoption. Full article

The objective of this study was to develop a stochastic simulation model to evaluate the impact of accelerated lambing on income over feed cost (IOFC) in Lacaune ewes managed under an intensive production system in Greece. The economic comparison of two lambing intervals (LI) was performed by varying the voluntary waiting period to allow for an 8-month LI (3 lambings in 2 years) versus a 12-month LI (1 lambing per year). Milk production per year was greater (p < 0.01) for the 8-month compared to the 12-month LI (777.4 ± 2.8 kg vs. 661.9 ± 2.1 kg, respectively), and the income from the sale of milk was greater for the 8-month compared to the 12-month LI (EUR 1166.0 ± 4.1 vs. EUR 992.9 ± 3.1, respectively). Feed cost per year was greater for the 8-month compared to the 12-month LI (EUR 255.9 ± 0.5 vs. EUR 227.8 ± 0.5, respectively). Therefore, IOFC per year was greater for the 8-month compared to the 12-month LI (EUR 989.4 ± 3.2 vs. EUR 817.1 ± 2.1, respectively). The cost per additional day open in the 12-month LI was estimated at EUR 1.08 ± 0.06 and demonstrates the importance of reproductive performance in the profitability of dairy sheep production. Therefore, reproductive management strategies that result in reduced LI are expected to increase IOFC in Lacaune dairy ewes. Future research is needed to develop practical strategies to successfully reduce the lambing interval in Lacaune ewes. Full article

We aimed to assess the seroprevalence of anti-Neospora caninum and anti-Toxoplasma gondii antibodies in cattle intended for human consumption in Paraíba, Brazil, and the associated risk factors. A total of 110 serum samples from slaughtered cattle were analyzed using the Indirect Fluorescence Antibody Test (IFAT), with cut-off points of 1:200 for N. caninum and 1:64 for T. gondii. Seroprevalence was 8.2% (9/110) for N. caninum (titers 1:200–1:6400) and 18.2% (20/110) for T. gondii (titers 1:64–1:512). Risk factor analysis revealed that the variable female sex (cows) and the extensive farming system were statistically significantly associated with seroprevalence for N. caninum. Whereas for T. gondii, extensive farming, frequent animal purchase, and the lack of separation between calves and adult cattle were statistically significant. These findings demonstrate the circulation of these parasites in herds, with implications for animal and public health, indicating a potential risk of transmission to definitive hosts and humans through the consumption of raw or undercooked infected meat. Full article

Livestock production raises significant environmental concerns, necessitating the development of sustainable feeding strategies based on non-conventional forages, such as locally available vegetation. This study evaluated the effects of a pelleted concentrate containing 10% Acacia farnesiana leaves as a dietary supplement on in vitro ruminal fermentation. Four experimental diets were formulated with increasing levels of the concentrate (0%, 25%, 50%, and 75%). Analyses were performed in triplicate and included chemical composition, in vitro gas and methane production, fermentation kinetics, ammonia nitrogen concentration (N–NH₃), in vitro dry matter digestibility (IVDMD), and metabolizable energy (ME) estimation. The results revealed no significant differences (p > 0.05) in most gas production kinetic parameters, overall fermentation patterns, or metabolizable energy. In contrast, a significant increase (p < 0.05) in secondary metabolite concentrations was detected. While methane production remained unaltered (p > 0.05), a significant linear reduction was observed for IVDMD, the lag phase (L), and N–NH₃ concentration (p = 0.0064, p = 0.0036, and p < 0.0001, respectively). These findings suggest that A. farnesiana can be incorporated into ruminant concentrates without increasing methane emissions. However, in vivo trials and mechanistic studies are required to validate and further elucidate these results. Full article

No studies have induced maternal behavior in goats through hormonal treatment. We evaluated whether ovariectomized goats treated with estradiol benzoate (EB2; n = 7 nulliparous and 10 multiparous goats) or progesterone + estradiol benzoate (P4 + EB2; n = 7 nulliparous and 7 multiparous goats), before or after vagino-cervical stimulation (VCS), displayed maternal behavior. When all goats were measured within treatments, in the EB2 group, low-pitch bleats were more frequent, and the time spent cleaning the kids was longer after VCS (p < 0.01), while location changes were more frequent before VCS. In nulliparous goats, those in the EB2 group emitted more low-pitch bleats after VCS than before (p = 0.04). The frequency of location changes was higher before VCS than after (p = 0.05). In multiparous goats, the frequency of smelling the kids and aggression toward the kids before VCS was higher in the EB2 group than in the P4 + EB2 group (p < 0.01). Within treatments, the EB2 group emitted more low-pitch bleats after VCS than before (p = 0.01), and the duration of cleaning the kids was longer after VCS than before (p = 0.028). Within the P4 + EB2 group, the kids were smelled more frequently after VCS than before (p = 0.03). The maternal index after vagino-cervical stimulation was higher in goats with EB2 (p = 0.002). Nulliparous goats treated with P4 + EB2 had a higher maternal index compared with those treated with EB2 alone (p = 0.04). In conclusion, regardless of parity, maternal behavior induced with the EB2 treatment was better when VCS was applied. Likewise, maternal experience altered the response. In multiparous females, any of the treatments were better after VCS, while in nulliparous females, this was only evident with the EB2 treatment. Full article