Search Results (88)

The risk of subacute ruminal acidosis (SARA) in grazing dairy cows remains uncertain, particularly when concentrates are supplemented. This study evaluated the effects of concentrate supplementation on the evolution of diurnal ruminal pH and its relationship with production, nutrient utilization, digestive indicators, and health status. Eight ruminal-fistulated multiparous Holstein–Friesian cows were assigned to a 2-period crossover design comparing a pasture-only diet (PO) and the same pasture supplemented with 6 kg/d of grain-based concentrate (PC). Each 28 d period included 21 d of adaptation and 7 d of measurements. Cows were fed freshly cut perennial ryegrass. Ruminal pH was recorded at 0, 2, 4, 6, 8, 10, 12, and 18 h relative to feeding. Concentrate supplementation slightly decreased minimum ruminal pH (5.97 vs. 6.15) but remained above the SARA threshold. Total volatile fatty acids (VFAs) increased, and acetate molar percentage decreased with supplementation. Total dry matter intake increased by 3.5 kg/d, increasing milk yield by 3.85 kg/d, and improving milk protein concentration, while milk fat and fatty acid profile, ruminal ammonium, and clinical indicators were unaffected. Ruminal pH was higher and VFA concentrations lower late in the season. Overall, concentrate supplementation was associated with improved productivity without compromising ruminal stability under the conditions of this study; however, responses were influenced by seasonal variation in pasture characteristics. Full article

Modern dairy production has greatly increased milk yield, but high productivity is often accompanied by greater metabolic pressure, particularly during the transition period. Ketosis, fatty liver, and subacute ruminal acidosis are major disorders that limit health, efficiency, and sustainability in high-yielding dairy ruminants. This review examines the rumen microbiota as a central biological interface linking diet, ruminal fermentation, epithelial function, hepatic metabolism, and inflammation. Under homeostatic conditions, the rumen microbiota supports lactation by converting dietary fibre, starch, and nitrogen into volatile fatty acids, microbial protein, and other metabolites required for gluconeogenesis, milk component synthesis, and epithelial maintenance. However, under excessive nutritional or physiological stress, especially high-concentrate feeding and periparturient negative energy balance, this system may shift toward dysbiosis, acid accumulation, lipopolysaccharide release, epithelial barrier impairment, and activation of gut–liver inflammatory pathways. These changes can contribute to the occurrence and interaction of subacute ruminal acidosis, ketosis, and fatty liver. We further summarize key factors affecting rumen microbial stability, including diet structure, host variation, physiological stage, environmental stress, feeding management, and ruminal epithelial volatile fatty acid absorption. Finally, microbiome-oriented strategies, such as gradual dietary transition, nutritional preconditioning, probiotics, postbiotics, functional metabolites, host metabolic support, and epithelial-targeted interventions, are discussed. Maintaining rumen microbial homeostasis should be regarded as a core principle for balancing high milk yield with long-term metabolic health. Future research should move beyond descriptive profiling toward causal validation of host–microbe interactions and the development of microbiome-based early-warning and individualized nutritional management systems. Full article

Rumenitis is an inflammatory condition of the rumen, typically seen in adult cattle managed on high-energy diets. In calves, it is uncommon and often linked to ruminal drinking due to esophageal groove dysfunction. Early diagnosis is challenging due to nonspecific clinical signs. A one-month-old male Limousin calf was presented with persistent non-fetid fluid regurgitation, rhythmic mastication, inappetence, and progressive neurological signs. Clinical examination revealed signs of dehydration and neurological dysfunction. Laboratory evaluation demonstrated metabolic acidosis (pH 7.16), hyperkalemia, and elevated serum urea. Endoscopy identified diffuse mucosal hyperemia, erosions, and fluid accumulation in the rumen. Symptomatic and supportive therapy was initiated; however, the calf died spontaneously. Necropsy was therefore performed, and rumen samples were collected for histological and microbiological investigations. Histopathological analysis confirmed acute suppurative rumenitis. The microbiological culture of rumen and reticulum samples yielded mixed bacterial flora, including Escherichia coli and Proteus mirabilis. The fungal culture isolated Penicillium spp., Mucoraceae, Geotrichium spp., and Aspergillus fumigatus. This case details the value of integrating clinical examination, blood gas analysis, endoscopy, histopathology, and microbiology in diagnosing rumenitis in young calves. Although Limousin calves are not considered predisposed, management and feeding practices may play a critical role in disease onset. Rumenitis should be considered in calves presenting persistent regurgitation and neurological signs. Early, minimally invasive diagnostics such as endoscopy can improve diagnostic accuracy and inform timely clinical decision-making. Full article

This study evaluated six supervised machine learning (ML) models for early detection of subclinical ketosis and low-grade ruminal acidosis in dairy cows during the transition period. Ninety-four Holstein cows were monitored for 21 days postpartum using in-line milk analyzers and intraruminal sensors that continuously recorded milk composition, behavioral, and physiological parameters. Based on clinical examination, blood β-hydroxybutyrate concentration, and fat-to-protein ratio, cows were classified as healthy (n = 44), subclinical ketosis (n = 24), or subclinical acidosis (n = 26). Among the tested models, Random Forest and XGBoost achieved perfect accuracy within this dataset, while Logistic Regression reached 89.5%, Decision Tree 84.2%, and both Naive Bayes and Support Vector Machine 78.9%. These results suggest that ensemble approaches, particularly Random Forest and XGBoost, show strong potential for integration with precision livestock technologies, but their apparent performance should be interpreted cautiously and confirmed in larger, multi-farm studies. Full article

Feeding a balanced diet such as total mixed ration (TMR) is a widely adopted feeding strategy providing a uniformly blended diet of roughages, concentrates, and supplements that enhances ruminant productivity by optimizing nutrient utilization, stabilizing rumen fermentation, and improving microbial activity. Scientific studies have confirmed that TMR increases dry matter intake (DMI), milk yield, and growth performance in dairy and beef cattle, as well as in sheep and goats. TMR’s advantages include consistent feed quality, reduced selective feeding, and improved feed efficiency. A key benefit of TMR is its ability to promote the production of volatile fatty acids (VFAs), which are the primary energy source for ruminants, particularly propionate. This enhances energy metabolism, resulting in higher carcass yields, increased milk production, and economic benefits compared to conventional or supplementary feeding systems. However, TMR feeding is also susceptible to mycotoxin contamination (e.g., aflatoxins, zearalenone), potential effects on methane emissions, and the need for precise formulation to maintain consistency and optimise profitability. Prevention and good practices, including routine inspection of feed for pathogens and vulnerable ingredients, as well as careful management of particle size and forage-to-concentrate ratios, are crucial in preventing subacute ruminal acidosis (SARA) and the development of other subclinical diseases. Mycotoxin binders, such as hydrated sodium calcium aluminosilicate, can also reduce mycotoxin absorption. Another advantage of practicing TMR is that it can support sustainable farming by integrating agro-industrial byproducts, which minimises environmental impact. In conclusion, TMR is a widely adopted feeding strategy that significantly enhances ruminant productivity by optimizing nutrient utilization, stabilizing rumen fermentation, and improving microbial activity, leading to increased dry matter intake, milk yield, and growth performance. It offers key benefits such as consistent feed quality, reduced selective feeding, improved feed efficiency, and enhanced energy metabolism, providing economic advantages and supporting sustainable farming through agro-industrial byproduct integration. However, its implementation requires careful management to mitigate risks, including mycotoxin contamination, potential impacts on methane emissions, and digestive issues like SARA if formulation is not precise. Therefore, for sustainable production, future research should focus on optimizing TMR formulations with alternative ingredients (e.g., agro-industrial byproducts) and precision feeding strategies to enhance livestock health and animal productivity while minimizing environmental impacts. Full article

Severe bushfires in South-Eastern Australia during the summer of 2019/2020 killed tens of thousands of livestock, while many more survived on fire-affected properties. At the time, the literature on bushfire and livestock in Australia primarily described animals with burns. The mid- to long-term health effects, if any, of fire exposure and the effectiveness of recovery activities for surviving animals and farm enterprises were rarely reported. This study aimed to describe the key impacts of bushfire exposure on the health, welfare, and management of surviving cattle and sheep to inform recommendations for future fire-affected farmers and to guide future research. As part of a broad research programme, data on bushfire experiences, consequences for the livestock and the farm enterprise, and lessons learnt were gathered through face-to-face interviews and an online survey, collating information from 58 fire-affected farmers. A variety of health conditions at low frequency were reported in livestock surviving bushfires, including respiratory disease, eye disease, ruminal acidosis, lameness, and plant toxicities. No single disease was observed widely across participating farms, with many conditions likely associated with management changes post-fire rather than direct fire exposure. A variety of management and farm biosecurity challenges were also described by farmers. Key strategies for the prevention and treatment of health conditions in livestock post-bushfire include supporting effective farm management through the challenges of post-fire recovery and early detection for treatment on a case-by-case basis. Full article

This study aimed to elucidate the therapeutic mechanisms of carbonate buffer mixture (CBM) in mitigating subacute rumen acidosis (SARA) by examining its effects on rumen pH, systemic inflammation, and rumen microbiota in a dairy goat model. Using a controlled experimental design, SARA was induced through 8-week high-concentrate diet feeding (70% concentrate, 30% forage), followed by 2-day CBM treatment. Comprehensive analyses included rumen pH monitoring, serum inflammatory marker quantification (IL-1β, TNF-α) by ELISA, rumen barrier integrity assessment through tight junction proteins (TJs) ZO-1, Occludin, and Claudin-3 by western blot analysis, and 16S rRNA sequencing of rumen microbiota. The results demonstrated that CBM administration rapidly elevated depressed rumen pH within 6 h post-treatment while concurrently reducing circulating LPS levels. The analysis of rumen 16S rRNA showed that CBM significantly increased the rumen microbial diversity and abundance of SARA dairy goats. Butyric acid generation groups such as Rikenellaceae_RC9_gut_group, NK4A214_group, and Prevotellaceae UCG-001 were selectively enriched, and corresponding functional predictions showed that the butyric acid synthesis pathway (PICRUSt2) was enhanced. These findings suggest that CBM has a multidimensional therapeutic effect by simultaneously correcting rumen acidosis, alleviating systemic inflammation, and restoring microbial balance through pH-dependent and pH-independent mechanisms, providing a scientifically validated nutritional strategy for SARA management in intensive ruminant production systems. Full article

Neem cake (Azadirachta indica) is a versatile plant with potential benefits for ruminant animals due to its effects on rumen modulation. This study aimed to evaluate the effects of increasing levels of neem cake and monensin on in vitro ruminal fermentation in cattle diets. Six treatments were tested: neem cake at 0, 240, 480, 720, and 960 mg/kg dry matter (DM) and monensin at 30 mg/kg DM. The basal diet consisted of a diet with a 15:85 roughage-to-concentrate ratio. Parameters evaluated included gas production kinetics, CH₄ and CO₂ emissions, pH, volatile fatty acids (VFAs), ammonia-N (NH₃-N), and organic matter digestibility. Neem cake increased ruminal pH compared to monensin (p < 0.01). The total VFAs increased linearly with neem cake inclusion (p < 0.01). The acetate proportion increased quadratically (p = 0.06). Propionate decreased linearly (p = 0.02), while branched-chain VFAs (BCVFAs) increased linearly (p = 0.09). The neem cake addition increased the NH₃-N concentration quadratically (p < 0.01). CH₄ and CO₂ concentrations were higher with neem cake compared to monensin (p < 0.05). Neem cake shows potential to reduce rumen acidosis and enhance fiber digestion, making it useful during the adaptation period for finishing diets in feedlots and for grazing animals. However, it was not effective in reducing greenhouse gas emissions in this in vitro system. Full article

Increasing the proportion of concentrate in diets can effectively improve ruminant production, and is therefore widely used. However, high-concentrate diets (HCD) enriched with rapidly fermentable carbohydrates can accelerate the production of lactate and short-chain fatty acids (SCFAs). The accumulation of lactate and SCFAs in the rumen leads to a reduction in rumen fluid pH, potentially resulting in subacute rumen acidosis (SARA), which can decrease dry matter intake (DMI), induce local and systemic inflammation, and cause other negative impacts on the host. The substantial prevalence of SARA attributable to long-term HCD causes considerable economic losses, as it can decrease DMI by up to 20%. Understanding its mechanisms and pathogenesis is essential. The rumen epithelium (RE), which is in direct contact with rumen fluid, is an important tissue in the rumen due to its roles in absorption, transport, and barrier functions. The changes that occur in RE under HCD and the subsequent impacts of these changes are worth exploring. In the short term, HCD feeding promotes RE cell proliferation and upregulates the activity of various transporter proteins, enhancing RE absorption and metabolism. However, with prolonged feeding, these functions of RE are negatively affected, accompanied by the development of inflammation. This review elucidates the structure, the functions, and the responses of RE under HCD, providing a detailed analysis of SARA pathogenesis at the cellular and molecular levels. Full article

Background: Cattle production is a cornerstone of U.S. agriculture but faces increasing pressure to balance profitability with environmental sustainability. Optimizing the ruminal microbiome to enhance feed efficiency could help address both challenges. Members of the Streptococcus bovis/Streptococcus equinus complex (SBSEC) are key contributors to ruminal acidosis and related digestive disorders due to their role in carbohydrate fermentation and lactic acid production. Bacteriophages targeting this bacterial group present a promising approach to mitigate this problem with high precision and without promoting the spread of antibiotic resistance. Methods: A collection of SBSEC-targeting bacteriophages were isolated from cattle rumen fluid and feces and further characterized. Characterization included host-range evaluation, whole genome sequencing, and growth inhibition assessment via optical density measurements. Selected bacteriophages underwent training to enhance infectivity. Results: Eleven lytic and one lysogenic phage were isolated. Several phages demonstrated sustained bacterial growth suppression, showing efficacy against SBSEC bacteria from diverse sources despite narrow host ranges. Co-evolutionary training was done in a subset of phages to improve bacteriolytic activity but had an inconsistent effect on the ability of phages to inhibit the growth of their naïve host. Genomic sequencing and phylogenetic analysis revealed uniqueness and clustering into three distinct groups that matched phenotypic characteristics. Conclusions: This study demonstrates the potential of bacteriophages as precise biological control agents, with successful isolation and enhancement of phages targeting SBSEC bacteria. Eleven lytic genome-sequenced phages show promise for development as cattle feed additives, though further research is needed to optimize their application in agricultural settings. Full article

As the key components of dietary carbohydrates, ensuring a balance between forage-neutral detergent fiber (FNDF) and rumen-degradable starch (RDS) is essential for ruminant health. Eight male Hu sheep equipped with rumen cannulas were randomly divided into four groups based on dietary FNDF content: low FNDF (L-FNDF, 6.08%), middle low FNDF (ML-FNDF, 9.47%), middle high FNDF (MH-FNDF, 12.48%), and high FNDF (H-FNDF, 15.68%), while the RDS levels (15.65% of DM on average) were similar among the four groups. A replicated 4 × 4 Latin square design was employed in this study. The results indicated that mean and minimum ruminal pH increased linearly with increasing dietary FNDF content, while the duration and area of pH under 5.8 and 5.6, along with the acidosis index, reduced linearly (p ≤ 0.002). There were no differences between the MH-FNDF group and the H-FNDF group in these indicators (p > 0.05). The molar proportions of acetate, butyrate, isobutyrate, and isovalerate, as well as the acetate-to-propionate ratio, increased linearly, while propionate and valerate molar proportions and lactate concentration displayed a linear decrease with increasing FNDF content in the diet (p < 0.001). Increasing dietary FNDF content extended ruminating and chewing time while enhancing ruminal microbial diversity, promoting the proliferation of Fibrobacterota and Butyrivibrio in the rumen, and improving fiber degradability (p < 0.05). When the dietary FNDF content exceeded 12.48%, no effects of FNDF on acetate to propionate ratio and fiber utilization were observed (p > 0.05). The results suggest that augmenting FNDF content in the PTMR can reshape ruminal fermentation towards acetate production and promote rumination to enhance ruminal pH, thereby alleviating the risk of ruminal acidosis. When the RDS content in the PTMR was 15.57%, an FNDF content of 12.48% was optimal for maintaining stable ruminal function in sheep, and the recommended ratio of FNDF to RDS was 0.8. Full article

This study was developed with the goal of exploring the impact of capsaicin on ruminal fermentation and ruminal bacteria in beef cattle affected by high-grain diet-induced subacute ruminal acidosis (SARA). In total, 18 healthy Simmental crossbred cattle were randomized into three separate groups (n = 6/group): (1) control diet (CON; forage-to-concentrate ratio = 80:20); (2) high-grain diet (SARA; forage-to-concentrate ratio = 20:80); and (3) high-grain diet supplemented with capsaicin (CAP; 250 mg/cattle/day). The study was conducted over a 60-day period. The results showed that the SARA model was successfully induced in the SARA group with a high-grain diet. Relative to the SARA group, the addition of capsaicin elevated the ruminal pH from 5.40 to 6.36 (p < 0.01), and decreased the total volatile fatty acids (VFAs) from 133.95 to 82.86 mmol/L (p < 0.01), aligning closely with the levels observed in the CON group. The addition of capsaicin increased the alpha diversity of ruminal bacteria relative to the SARA group, as evidenced by a lower Simpson index (p < 0.05), together with increases in the Ace, Chao, and Shannon indices (p < 0.05). Bacteroidota and Firmicutes were the most common phyla across all treatment groups, while Prevotella was the predominant genera. The unique bacterial genera (LDA scores > 4) identified within the SARA group comprised Succinivibrionaceae_UCG-001, Succinivibrio, NK4A214_group, Lachnospiraceae_NK3A20_group, and Ruminococcus, which may serve as potential biomarkers for the diagnosis of SARA. The unique genera associated with the CON group included Rikenellaceae_RC9_gut_group, Prevotellaceae_UCG-003, and U29-B03, while those for the CAP group included Succiniclasticum and Prevotellaceae_UCG-004. In summary, these results suggest that dietary capsaicin supplementation can limit the adverse effects of SARA through the modulation of bacterial communities within the rumen, thus altering ruminal fermentation in beef cattle. Full article

Subacute rumen acidosis (SARA) is a significant concern in dairy cattle fed grain-rich diets. To elucidate the underlying pathophysiological mechanisms, ruminal papilla biopsies are often used. This study aimed to assess how the sampling site along the ruminal papilla influences gene expression profiles in rumen epithelium during SARA. Rumen biopsies from five ruminal-cannulated non-lactating Holstein cows were collected during feeding of a forage diet (FD) and seven (wk1) and 21 days (wk3) after transition to high-grain (HG) feeding. Gene expression in apical (AP), basal (BP), and total length (TP) papillae were compared using RT-qPCR. Significant diet-induced effects were observed in AP for DSG1 (wk3, p = 0.0317), ZO1 (wk1 and wk3, p = 0.0159), GLUT3 (wk3, p = 0.0159), TLR4 (wk3, p = 0.0635), and NFKB (wk1, p = 0.0159), but hardly in BP or TP. Within wk1, TP showed higher transcript levels of ZO1 and TLR4 (p = 0.0079) and SGLT1 (p = 0.0317) compared to AP and BP independently from diet effects. These findings suggest that the apical parts of rumen papillae biopsies are most suitable for gene expression analyses to investigate diet-induced effects on rumen physiology and underscore the importance of considering the sampling site for accurate gene expression studies in rumen epithelium during SARA, providing valuable insights for future research and diagnostic approaches in managing rumen health in dairy cattle. Full article

This study aimed to explore the effects of sodium butyrate on liver metabolism in goats subjected to a high-concentrate diet. We randomly assigned twelve Saanen-lactating goats into two groups, one of which received a high-concentrate diet (concentrate: forage = 60:40, control group), while the other received the same basal diet supplemented with sodium butyrate (SB) (10 g/kg basal diet, SB group). Compared with the control diet, the SB diet considerably increased the milk fat percentage and content (p < 0.05), with an increase of 0.67% in the milk fat content of the SB group. By employing a global metabolomics approach based on ultra-performance liquid chromatography–tandem mass spectrometry (UPLC–MS/MS), we identified 6748 ions in ESI+ mode and 3573 ions in ESI− mode after liver isolation from both groups. A total of twenty-three metabolites, including phospholipids, fatty acids, and ribose phosphate, were found to be dysregulated according to a search against the human metabolome database (HMDB). Pathway analysis revealed activation of the pentose phosphate pathway, glycerophospholipid metabolism, and unsaturated fatty acid synthesis. The SB diet also modulated the expression of key lipogenic enzymes, such as acetyl-CoA carboxylase (ACC) and stearoyl-CoA desaturase (SCD-1), which are downstream targets of the transcription factor sterol regulatory element-binding proteins-1c (SREBP-1c), inducing a significant upregulation (p < 0.05). Furthermore, 6-phosphogluconate dehydrogenase (6PGDH) levels in the liver were elevated after the lactating goats were fed the SB diet (p < 0.05). Our study reveals that the SB diet may offer substantial benefits in enhancing the milk quality of subacute ruminal acidosis (SARA) goats. This is accomplished by augmenting the activity of the liver pentose phosphate pathway and the process of de novo fatty acid synthesis in lactating goats. Full article

Subacute ruminal acidosis (SARA) is a prevalent metabolic disorder in highly productive dairy cows that results in serious issues, including hoof lamellar injuries. This study aimed to investigate the efficacy of a carbonate buffer mixture (CBM) in preventing hoof lamella injury in dairy goats, a species also susceptible to SARA due to similar feeding practices over a 17-week period. Twenty-four healthy dairy goats were randomly assigned to three groups: control, SARA, and CBM groups. The control group received a standardized diet, whereas the SARA and CBM groups were subjected to a high-grain feeding regimen to induce SARA. The CBM group received a daily supplement of 10 g CBM mixed with their diet. Clinical assessments, including body temperature, rumen pH, inflammatory markers, matrix metalloproteinases (MMPs), and hoof lamellar injuries, were monitored throughout the study. The results showed that the CBM group maintained a more stable rumen pH and had lower levels of inflammatory markers than the SARA group did. The incidence of hoof lamellar injury was slightly lower in the CBM group. These findings suggest that long-term CBM supplementation may mitigate SARA-associated hoof lamella injury in dairy goats by regulating the rumen environment, fostering the growth of healthy bacterial communities, and by reducing the production of harmful metabolites. The use of CBM as a dietary supplement may have significant implications in improving the health, welfare, and productivity of dairy animals. Full article