Search Results (474)

The early-life rumen microbiome is highly dynamic, shaped by dietary transitions and maternal influences. Several dietary additives have been studied during the pre- and post-weaning periods to improve animal welfare, growth performance, and farming efficiencies. This study investigated microbial community assembly and growth performance of lambs provided with a mannan-rich fraction (MRF) supplement, either through maternal supplementation, directly, or via a combination of both. Using metagenomic sequencing and gas chromatography, we found differences in rumen microbial alpha and beta diversity related to both sampling time point and MRF supplementation (p < 0.05). At week 8, lamb microbiomes showed greater variance in their Shannon alpha diversity, with direct MRF supplementation only to the lamb resulting in a significantly greater diversity (p < 0.05). At week 20, combined maternal and lamb supplementation resulted in the highest Shannon diversity and was different compared to all other groups (p < 0.05). Beta diversity analyses combined with differential abundance analyses revealed that microbial community structures are driven by both diet and time, with maternal MRF supplementation associated with enrichment of taxa involved in carbohydrate fermentation and succinate metabolism, including Succiniclasticum ruminis, Succinovibrio dextrinosolvens, and Fibrobacter succinogenes. Generalized linear modeling identified significant associations between microbial alpha diversity metrics and total volatile fatty acids in lambs, particularly butyrate and valerate. Furthermore, at week 8, there was a significant positive correlation between alpha diversity metrics and propionate and valerate. In this study, lambs receiving MRF through maternal and direct supplementation had the highest growth performance, measured as the median average daily gains (kg) and final weights (kg) of lambs. These findings suggest that MRF supplementation, especially when provided both maternally and directly, may influence the lamb rumen microbiome and alter its metabolic potential with potential implications for optimizing early-life nutrition strategies in ruminant production systems. Full article

Milk fat synthesis in dairy cows is a complex process affected by ruminal fermentation, systemic metabolism, and mammary gland activity. To explore the metabolic interplay across these systems, a multi-tissue metabolomics approach (rumen fluid, plasma, and milk) using ultra-high-performance liquid chromatography–mass spectrometry was used to identify metabolic differences between Chinese Holstein cows with high (H-MF, 5.82 ± 0.41%) and low (L-MF, 3.60 ± 0.12%) milk fat content under the same diet. The bovine mammary epithelial cells (BMECs) were also cultured to evaluate the impact of a key metabolite, malic acid (MA), on lipid metabolism. Our findings reveal distinct metabolic profiles across rumen fluid, plasma, and milk, with 96, 109, and 79 differential metabolites, respectively, between the L-MF and H-MF groups. In rumen fluid, H-MF cows showed higher levels of lauric acid and succinic acid, linked to fatty acid biosynthesis, while the L-MF cows had elevated citraconic and orotic acids, associated with amino acid metabolism and liver stress. Plasma from the H-MF cows contained higher β-hydroxybutyric acid, methionine sulfoxide, and phosphatidylcholine, supporting lipogenesis, whereas L-MF plasma showed increased 3-hydroxy-L-proline, indicating tissue catabolism. In milk, the L-MF cows had higher MA, while the H-MF cows exhibited elevated L-carnitine, linked to fatty acid β-oxidation. Metabolite trend analysis during rumen fluid–plasma–milk showed that 211 metabolites were classified into 8 profiles. Profile 1 had the largest number of metabolites whose levels were down-regulated from rumen to plasma and enriched in lipid metabolism. Profile 3 (mainly related to amino acid metabolism) and profile 4 (mainly related to energy metabolism) exhibited opposite trends from plasma to milk. In vitro, 200 μM of MA reduced the triglyceride content in BMECs and down-regulated lipogenic genes and their protein expression levels (fatty acid synthase, stearoyl-CoA desaturase and sterol regulatory element binding protein 1). These results highlight how rumen fluid, plasma, and milk metabolites collectively influence milk fat synthesis, with MA acting as a key regulator of lipid metabolism in mammary epithelial cells. Full article

Modern genetic selection for high productivity has created a physiological conflict in ruminants, where the metabolic demands of lactation compete directly with the energy requirements of reproduction. This review provides a mechanistic synthesis of how key nutritional factors modulate the endocrine and cellular pathways governing reproductive success in cattle and sheep. Negative energy balance (NEB), characteristic of the early postpartum period, suppresses the hypothalamic–pituitary–gonadal (HPG) axis by impairing the pulsatile secretion of gonadotropin-releasing hormone (GnRH) and luteinizing hormone (LH), mediated through reduced kisspeptin signaling, growth hormone (GH) resistance, and decreased circulating insulin, insulin-like growth factor-1 (IGF-1), and leptin. At the macronutrient level, excess rumen-degradable protein elevates blood urea nitrogen and impairs the uterine environment, while omega-3 polyunsaturated fatty acids inhibit prostaglandin F2α synthesis to support corpus luteum maintenance. At the micronutrient level, selenium, copper, and zinc are essential antioxidant cofactors protecting gametes and embryos from oxidative stress, while vitamins A, D, and E regulate gene expression in reproductive tissues. Furthermore, maternal nutrition during critical gestational windows programs the reproductive capacity of offspring through epigenetic modifications, with profound implications for long-term herd fertility. Understanding these nutritional–reproductive interactions is crucial for developing precision feeding strategies that optimize herd fertility, improve animal welfare, and ensure the economic sustainability of livestock management. A thorough understanding of these nutritional–reproductive interactions is essential for developing precision feeding strategies that optimize fertility in high-producing ruminants. Full article

This study evaluated the effects of forage-free diets with reduced starch levels on the productive performance, metabolism, ruminal fermentation, nutrient digestibility, and meat quality of feedlot beef cattle. Two experiments were conducted. In Experiment 1, forty uncastrated Nellore steers were distributed into 20 pens in a completely randomized design, receiving diets with increasing inclusion levels of ground corn in the total diet: C400 (400 g kg⁻¹), C200 (200 g kg⁻¹), C100 (100 g kg⁻¹), and C50 (50 g kg⁻¹), formulated without forage and based on fibrous co-products. Increasing ground corn inclusion promoted linear improvements in final body weight and average daily gain, while dry matter intake and feed efficiency showed quadratic responses. Meat quality parameters were not affected by dietary treatments. In Experiment 2, eight crossbred steers were assigned to a double 4 × 4 Latin square design and fed the same experimental diets. Higher corn inclusion increased starch and fat intake, whereas dry matter, organic matter, and protein intake showed quadratic responses. Apparent total-tract digestibility of dry matter, organic matter, and starch also followed a quadratic pattern. Ruminal fermentation parameters were affected by dietary treatments, with greater ammoniacal nitrogen concentrations at higher corn levels and quadratic responses for propionate, butyrate, and methane production. Nitrogen metabolism indicated increased urinary nitrogen and uric acid excretion with increasing dietary corn inclusion. These results demonstrate that forage-free diets based on citrus pulp and soybean hulls with different levels of ground corn can be effectively used in finishing beef cattle, improving performance without impairing meat quality while modulating ruminal fermentation and nutrient utilization. Full article

Rumination time is considered a sensitive behavioral indicator of physiological and metabolic status in dairy cows, yet its relationships with biochemical and milk quality parameters under commercial robotic milking conditions remain insufficiently described. This study combined precision monitoring technologies, serum biochemical profiling, and in-line milk analysis to evaluate physiological differences among early-lactation Holstein cows according to rumination time. A total of 88 cows were classified into three rumination time categories (>527, 412–527, and <412 min/day). Milk production traits, milk quality indicators, and blood biochemical parameters were compared among groups, and univariable regression analysis was performed to identify variables associated with rumination time. Cows in the low rumination group showed higher milk temperature, electrical conductivity, and somatic cell count, as well as lower milk protein percentage. They also showed higher concentrations of total protein, urea, gamma-glutamyl transferase, and lactate dehydrogenase, while triglyceride concentrations were lower. Regression analysis identified electrical milk conductivity, creatinine, magnesium, potassium, and chloride as variables associated with rumination time. These findings indicate that reduced rumination time is associated with changes in milk quality and biochemical parameters in early-lactation dairy cows, suggesting that rumination monitoring may provide useful information for identifying cows experiencing physiological and metabolic challenges under commercial farming conditions. Full article

This study aimed to investigate the changes in the meat quality characteristics of Duolang sheep using rumen metagenomic and muscle metabolomic analyses across different age groups. A total of 24 three-month-old male Duolang sheep were selected and reared, and samples of longissimus thoracis muscle and rumen contents were collected at 4, 6, and 8 months of age to evaluate meat quality, metabolites, rumen metagenome, and volatile fatty acids (VFAs). The results indicated that the lightness (L*_45min) and yellowness (b*_45min) of the longissimus thoracis muscle at 45 min post-slaughter were significantly higher at 4 and 6 months than at 8 months of age (p < 0.05). In terms of ruminal VFAs, butyrate concentration was significantly higher at 6 months than at 4 months (p < 0.05), and valerate concentration exhibited a quadratic relationship with age (p = 0.02). With increasing age, the relative abundances of Prevotella and Fibrobacter increased, whereas those of Methanobrevibacter and Bacteroides decreased (p < 0.05), leading to shifts in functional pathways related to amino acid, lipid, and carbohydrate and energy metabolism. Untargeted metabolomics revealed that muscle betaine and inosine peaked at 4 months of age, whereas L-arginine, L-proline, and inosinic acid were most abundant at 6 months of age (p < 0.05). Correlation analysis revealed that the b*_45min was positively associated with ruminal concentrations of propionate, butyrate, and valerate, as well as with the relative abundances of key Selenomonadales taxa (p < 0.05). Inosinic acid exhibited a positive correlation with the abundance of the genus Sodaliphilus and ruminal butyrate concentration (p < 0.05), while Sodaliphilus abundance was negatively correlated with inosine (p < 0.05). In summary, this study demonstrates that age-related variations in the meat quality of Duolang sheep are closely associated with rumen microbial ecology and muscle metabolites, offering novel insights into the molecular mechanisms underlying meat quality formation and identifying potential biomarkers. Full article

Prostaglandin E₂ (PGE₂) plays a critical role in regulating uterine endometrial function and supporting embryonic development during early pregnancy in ruminants. However, its precise roles in shaping the uterine microenvironment remain unclear. Herein, 1 mg PGE₂ was infused daily into the uterus of dairy heifers from days 12 to 14 of the estrus cycle. ULF was subsequently collected for integrated proteomic, metabolomic, and targeted lipidomic analyses. In addition, bovine endometrial epithelial cells were used to evaluate the effects of PGE₂ on epithelial adhesion and responsiveness to interferon tau (IFNT). PGE₂ infusion resulted in 909 differentially abundant proteins (DAPs), which are primarily associated with early embryonic development, immune regulation, and cell adhesion. Untargeted metabolomics analysis identified 587 altered metabolites, which were enriched in sphingolipid, arachidonic acid, phenylalanine, and tryptophan metabolism. Proteomic–metabolomic analyses showed that these alterations were primarily associated with early embryonic development, immune regulation, and cell adhesion. Targeted lipidomic analysis showed a global reduction in lipid accumulation, with glycerophospholipid metabolism and choline metabolism most significantly affected. In vitro, PGE₂ reduced epithelial microvilli density, increased osteopontin (OPN) expression, and decreased the expression of junctional proteins (zona occludens-1 (ZO-1), E-cadherin (CDH1), and fibronectin 1 (FN1)). Moreover, PGE₂ enhanced the responsiveness of bEECs to IFNT by interferon alpha/beta receptor 1 (IFNAR1) and IFNAR2, and prostaglandin E receptor 4 (PTGER4) was identified as the primary receptor mediating this response. Collectively, these findings suggest that PGE₂ may modulate lipid metabolism and adhesion-related processes in the endometrium and influence endometrial responsiveness to IFNT, providing insights into molecular mechanisms associated with pregnancy establishment in dairy cows. Full article

Oxidative stress contributes to reproductive disorders, immune dysfunction, and reduced productivity in livestock during periods of high metabolic demand and environmental challenge. Selenium supports antioxidant defense systems because it is incorporated as selenocysteine into selenoproteins, including glutathione peroxidases and thioredoxin reductases that detoxify peroxides and sustain redox balance. The review summarizes selenium occurrence and chemical forms in feeds, as well as its absorption, transportation, and storage. The review also outlines the major features of selenoprotein biosynthesis and its prioritized allocation, with an emphasis on cattle, pigs, sheep, and goats. Evidence from multiple sources indicates that selenium status and supplementation interacts with antioxidant capacity, immune competence, thyroid hormone metabolism, reproductive performance, and the transfer of selenium to milk and offspring. In ruminants, rumen microbial transformations can reduce the bioavailability of inorganic selenium salts, and organic sources, such as selenium-enriched yeast, hydroxy-selenomethionine, and selenitetriglycerides, often increase blood and milk selenium more effectively. In pigs, organic selenium is commonly associated with enhanced antioxidant and immune indices in sows and piglets during late gestation, lactation, and weaning, whereas effects on growth performance are inconsistent. The review emphasizes the narrow margin between adequacy and excess and outlines practical considerations for supplementation and monitoring, alongside research needs for emerging selenium forms and functional biomarkers. Full article

Reducing enteric methane emissions from ruminants has emerged as a critical environmental priority in the face of global climate change, given the substantial contribution of methane to agricultural greenhouse gas outputs. This study evaluated the potential of spearmint essential oil (SEO) to reduce methane production and enhance energy utilization efficiency using an in vitro rumen fermentation system. The experiment comprised a control (CON, no additive), three SEO doses (L-SEO: 100 mg/L; M-SEO: 200 mg/L; H-SEO: 400 mg/L), and a commercial essential oil blend (AGL: 150 mg/L). Results indicated that M-SEO and H-SEO significantly reduced methane production at 24 h from 58.11 mL/g DM in CON to 47.93 and 46.58 mL/g DM, respectively (p < 0.001), corresponding to reductions of 17.5% and 19.8%. Furthermore, M-SEO increased total volatile fatty acid concentration from 48.41 to 58.10 mmol/L and elevated the molar proportion of propionate, while significantly enhancing microbial crude protein production (p < 0.001). Microbial community analysis revealed that M-SEO increased bacterial alpha-diversity (Shannon index) (p = 0.001) and significantly enriched specific functional guilds, particularly the propionate-producing genus Succiniclasticum and the butyrate-producing genus Butyrivibrio. Interestingly, the abundance of dominant methanogens (Methanobrevibacter) was not reduced, suggesting a metabolic inhibition mechanism rather than a biocidal effect. Functional prediction analysis further supported this, indicating a downregulation of pathways associated with methanogenesis, including key enzymes such as methyl-coenzyme M reductase. In conclusion, SEO supplementation at 200 mg/L effectively reduced methane production by redirecting metabolic hydrogen toward propionate formation, without affecting overall fermentation. Therefore, the current study indicated that SEO could serve as a sustainable feed additive for mitigating enteric methane emissions in ruminants. Full article

High-concentrate diets are widely used to enhance growth performance in fattening beef cattle; however, they often compromise rumen epithelial integrity, increasing the risk of rumenitis and systemic inflammation. Supplementation with alkaline mineral complex (AMC) has been shown to alleviate these adverse effects, although the underlying mechanisms remain largely unexplored. In this study, AMC supplementation was associated with improved rumen epithelial integrity and remodeling of the rumen microbiota, characterized by a reduction in Bacteroidota and Prevotella, and an enrichment of Sarcina sp. DSM11001 and Fibrobacter spp., with the latter identified as a key microbial biomarker in the AMC group. Integrated metabolomic and transcriptomic analyses revealed activation of the tryptophan metabolism pathway and accumulation of several anti-inflammatory metabolites, including sulfinpyrazone, Thr-Leu, and 4-guanidinobutyric acid. These metabolomic changes were correlated with the upregulation of tight junction pathways and increased expression of related proteins, which in turn were associated with enhanced epithelial barrier integrity and reduced systemic inflammation in the AMC group. Collectively, these findings suggest that AMC supplementation may protect rumen epithelial integrity by modulating the microbial community and altering ruminal metabolite profiles. This study provides insights into nutritional strategies to prevent epithelial damage under high-concentrate feeding conditions and support the potential use of AMC to maintain rumen health in fattening cattle. Full article

Volatile fatty acids (VFAs), the primary end-products of microbial fermentation in the ruminant forestomach, supply approximately 70% of the host’s energy requirements and play a pivotal role in maintaining energy homeostasis. While the mechanisms governing ruminal VFA production, absorption, and metabolism are well-characterized in common ruminants like dairy and beef cattle, a systematic integration of these processes in yaks, an iconic species long-adapted to the extreme Qinghai–Tibet Plateau, remains incomplete. This review synthesizes current knowledge on the entire VFA pathway in the yak rumen, from production to tissue metabolism. We detail the critical roles of functional microbes, including fibrolytic bacteria and Prevotella, in VFA synthesis and how their activity is dynamically regulated by dietary composition and seasonal shifts. Building on the unique structural features of the yak rumen epithelium, the review analyzes VFA absorption mechanisms involving both passive diffusion and carrier-mediated transport. Furthermore, we systematically outline the metabolic fates and energy partitioning strategies of VFAs across the rumen epithelium, liver, and peripheral tissues. This synthesis aims to elucidate the highly efficient and adaptive physiological basis of VFA metabolism that underpins the yak’s exceptional ability to utilize energy under the low-energy conditions of the high-altitude environment. Ultimately, this work seeks to provide a theoretical foundation for understanding plateau-adapted energy efficiency and to inform precision nutritional strategies for ruminants in alpine regions. 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

Residual lignin generated by pulp, paper, and biorefining industries is commonly burned for energy, despite its potential as a renewable source of aromatic compounds. Studies focusing on microbial lignin degradation contribute to lignin valorization and represent a sustainable strategy to enhance biomass circularity. Here, we report the isolation of Klebsiella sp. IL2_9 from a ruminal consortium and demonstrate its ability to degrade and metabolize organosolv lignin. After 24 h of cultivation, the strain removed 22% of the initial lignin content. FTIR analysis revealed alterations in functional groups associated with guaiacyl and syringyl units, indicating structural modification of the polymer. GC–MS analyses further showed the consumption of lignin-derived aromatics, including vanillin, 2-aminobenzoic acid, and 4-hydroxybenzoic acid, along with the formation of vanillyl alcohol and phenyllactic acid derivatives. Overall, these findings highlight the potential of Klebsiella sp. IL2_9 as a promising biotechnological candidate for lignin valorization under anaerobic conditions. Full article

This study evaluated the effects of increasing proportions of sudangrass sorghum forage in ruminant diets, with or without polyethylene glycol (PEG), on rumen fermentation, gas and methane production, nutrient digestibility, and protein fermentation metabolites. Three experimental diets containing 20%, 40%, or 60% sorghum forage (S20, S40, and S60) were incubated in vitro with cattle rumen fluid. Incubations were performed with or without PEG used as a tannin-binding agent. After 24 h of incubation, gas and methane production, in vitro dry matter digestibility (DMD), neutral detergent fiber digestibility (NDFD), ammonia nitrogen concentration (N-NH₃), and volatile fatty acid (VFA) production and profiles were measured. Increasing sorghum inclusion resulted in a significant reduction in DMD (p = 0.0012). In contrast, NDFD increased (p = 0.0005), likely due to differences in lignin content among diets. Methane production was unaffected by the proportion of sorghum, despite the increasing tannin content. PEG supplementation significantly increased N-NH₃ concentration (p = 0.042) and isobutyric molar proportion (p < 0.0001), indicating enhanced rumen protein degradation following tannin neutralization. The total VFA concentration was not influenced by either sorghum level or PEG treatment. However, higher sorghum inclusion was associated with shifts in the VFA profiles toward higher acetate (p = 0.0023) and lower butyrate proportions (p = 0.0114). Overall, the results suggest that moderate levels of condensed tannins (CTs) in sorghum forage may alter rumen fermentation patterns without markedly reducing methane production. PEG supplementation further confirmed the biological activity of tannins, especially regarding protein metabolism. Therefore, sudangrass sorghum may be considered a viable forage option for ruminant diets, provided its inclusion level and tannin effects are carefully managed. Full article

In vitro studies were conducted in a series to investigate if the ruminal microbes are capable of degrading chlorpyrifos. This in vitro study presents the results from three experiments: Exp. I was conducted without feed, while Exp II and III were conducted with feed, either with or without methanol for dissolving chlorpyrifos, respectively. A basal diet comprising finger millet straw and concentrate was prepared. Incubation medium with feed but without chlorpyrifos served as the control. A total of six replicates each of control and chlorpyrifos spiked were used for the incubation. The pesticide concentration in the incubation medium before and after 24 h of incubation was analyzed using GC-MS/MS. The genomic DNA was isolated from the incubation fluid of the individual samples, and the shotgun metagenomic sequencing was performed. The clean reads were taxonomically classified using the Kraken2 database, and microbial classification at different taxonomic ranks was separated using Pavian v1.0. The microbial genes in the metagenome data were predicted and assigned functional roles using the MetaErg v1.2.3 pipeline. The assigned KEGG Orthology (KO), EC numbers (Enzyme Commission number), Gene Ontology (GO), and corresponding NCBI taxonomy information relevant to chlorpyrifos metabolism/degradation were retrieved. Results from the study revealed that the chlorpyrifos concentration was decreased from 5.78 to 1.64 ppm over 24 h of in vitro incubation with feed. Similar alpha and beta diversity indices between control and chlorpyrifos treatments revealed that the richness and the evenness of the microbial population were not affected by the presence of chlorpyrifos in the rumen fluid. There was no difference in the microbiota affiliated to the major phyla such as Bacteroidota, Fibrobacterota, Bacillota, and Pseudomonadota. The EC 3.1.8.1, EC 3.1.3.1, EC 1.14.13.-, and EC 1.1.1.- reported for chlorpyrifos degradation were not detected in the metagenome, and only EC 3.1.1.1 was identified, which demonstrated that degradation of chlorpyrifos was carried out by the affiliated enzyme carboxylesterase. The presence of GO:0004035, GO:0004364, GO:0019637, GO:0016791, and GO:0042178 in the metagenome strengthens that the chlorpyrifos degradation in the present study was primarily assigned to the rumen microbiota. This in vitro study provided insights into the rumen microbiota involved in the chlorpyrifos degradation and the initial clue that the rumen microbes are capable of degrading chlorpyrifos. Further, the animal studies in different species with the variable levels of chlorpyrifos are also warranted to confirm the efficacy of rumen microbes in mixed syntrophy and determine the threshold capabilities of the ruminal microbes. Full article