Search Results (114)

Background/Objectives: This study evaluated the effects of a compound probiotic fermented feed (CPFF) containing Lactobacillus plantarum, Bacillus subtilis, yeast, and Aspergillus niger on rumen in vitro fermentation, in situ feed degradation, and growth performance in beef cattle. Methods: We established a control group (CON) and experimental groups with 2%, 4%, and 8% CPFF supplementation for in vitro fermentation. Results: The results indicated that the NH₃-N concentration in the 4% CPFF group was significantly higher than in the other groups (p < 0.001). Similarly, microbial crude protein (MCP) production was significantly greater in the 4% CPFF group compared to the CON group (p = 0.016). The molar proportions of acetate, butyrate, isobutyrate, and valerate were significantly higher in the 2% and 4% CPFF groups than in the control group (p < 0.001), while propionate levels were significantly lower (p < 0.001). After 48 h, gas production was highest in the 4% CPFF group. Based on improvements in gas production, MCP synthesis, and fermentation intensity, the 4% inclusion level was determined to be optimal for further studies. We conducted an in situ degradation trial using 4% CPFF. Results showed that at 12 h, the neutral detergent fiber (NDF) degradation rate in the 4% CPFF group was significantly higher than in the CON group at 4, 8, 12, and 48 h (p < 0.05). At 48 h, the acid detergent fiber (ADF) degradation rate in the 4% CPFF group was also significantly higher than in the CON group (p < 0.001), and this group exhibited a significant increase in crude protein (CP) degradation (p = 0.030). We analyzed rumen fluid samples from both the CON and 4% CPFF groups after in vitro fermentation using 16S rRNA sequencing and untargeted metabolomics. Microbial community analysis revealed significantly increased abundances of functional bacterial groups such as Rikenellaceae_RC9_gut_group, Christensenellaceae_R-7_group, and UCG-002 in the 4% CPFF group (p < 0.05). Differential metabolites were primarily involved in pathways related to tryptophan metabolism, and tyrosine metabolism signaling. A feeding trial was conducted by adding 4% CPFF to the diet of Angus growing cattle. The results indicated that average daily gain (ADG) (p = 0.004) and average daily feed intake (ADFI) (p = 0.001) were significantly higher in the CPFF group than in the CON group. Conclusions: In conclusion, our results demonstrate that CPFF enhances rumen fermentation activity, optimizes the microbiota and metabolic profiles of rumen fluid, and improves the average daily gain of beef cattle. This research provides a valuable theoretical basis for applying CPFF in beef cattle breeding. Full article

Anti-nutritional factors (ANFs) in terrestrial plant feeds constrain efficient herbivore production, an issue intensified by rising feed costs and growing demand for animal products. Unlike previous reviews that focus on single ANFs or feed types, this review provides an integrated, cross-species framework linking ANF chemistry, rumen microbial interactions, and mitigation strategies. It examines major ANF classes—tannins, phytates, saponins, oxalates, protease inhibitors, lectins, glucosinolates, and gossypol—and their distribution and biochemical modes of action. Mechanistic pathways are grouped into digestive effects (reduced palatability and enzyme inhibition), microbial effects (altered rumen microbiota and fermentation), metabolic effects (impaired absorption), and mineral interactions (nutrient complexation and chelation). Species-specific responses are evaluated, emphasizing the partial detoxification capacity of the rumen microbiome and the dose-dependent nature of ANF effects. Mitigation strategies—physical, chemical, microbial, enzymatic, probiotic, and genetic—are critically assessed for efficacy, scalability, and sustainability. Emerging metabolomic and metagenomic evidence shows that certain ANFs confer functional benefits at controlled doses; for example, tannins improve nitrogen retention, saponins reduce methane, and phytic acid scavenges free radicals. This synthesis supports strategic management rather than complete elimination, informing safe and sustainable use of terrestrial feeds under evolving food-security and environmental challenges. Full article

High-yielding dairy cows are highly susceptible to lactational oxidative stress, which compromises mammary barrier integrity and elevates mastitis risk. This study investigated the potential biological mechanisms by which dietary hydroxy-selenomethionine (HMSeBA) alleviates oxidative stress and improves health in dairy cows. Forty Holstein cows were assigned to a basal control group (0.32 mg Se/kg DM) or an HMSeBA-supplemented group (0.64 mg Se/kg DM) for 105 days. HMSeBA significantly enhanced selenium bioavailability in both milk and blood, comprehensively strengthening antioxidant defenses (increased glutathione peroxidase activity, decreased malondialdehyde) and elevated serum immunoglobulins (IgA, IgM, IgG), accompanied by a reduction in milk somatic cell count, without significantly affecting milk yield, feed intake, or milk production efficiency. Multi-omics analysis revealed that HMSeBA supplementation altered the rumen microenvironment by enriching fiber-degrading genera (Prevotellaceae_Ga6A1_group, Xylanibacter, Segatella) and shifting metabolites, including feed flavonoids, peptides, 1-deoxy-D-xylulose-5-phosphate, and 3-OH-C6-HSL. The positive correlation of ruminal 3-OH-C6-HSL with both blood selenium and these enriched taxa suggests a potential link between microbial activity and host selenium status. These findings indicate that HMSeBA supplementation improves the antioxidant and immune status of dairy cows, accompanied by exploratory, hypothesis-generating shifts in the ruminal microbiome and metabolome. Collectively, these findings highlight HMSeBA as a promising nutritional strategy to produce selenium-enriched milk while safeguarding udder health. Full article

Background/Objectives: Exposure to high and sustained levels of non-esterified fatty acids (NEFA) in the peripartal period is the main cause of fatty liver disease in dairy cows. Rumen-protected choline is often fed as part of the nutritional management of peripartal cows, with in vivo and in vitro data indicating positive effects of this nutrient on alleviating liver lipid accumulation. Although hepatic molecular mechanisms associated with choline supply have been studied using a target gene, protein, or metabolite approach, application of high-throughput technologies could vastly enhance fundamental knowledge on the functional role of choline. The main objective was to challenge isolated hepatocytes with a mixture of NEFA and determine proteome- and metabolome-wide effects in response to choline supply. Methods: Three healthy female calves (1 d old, 30–45 kg) were sacrificed to harvest hepatocytes. During a 12 h incubation, isolated hepatocytes were challenged without NEFA (control), 1.2 mM NEFA (c9-18:1, 18:2, 16:0, 18:0, and c9-16:1 at 43.5%, 4.9%, 31.9%, 14.4%, and 5.3% of total NEFA, respectively), or NEFA for 6 h followed by 10 μM choline chloride for another 6 h (NEFA + Chol). iTRAQ labeling-based protein profiling and GC/MS-based metabolomics profiling were used to determine changes in proteins and metabolites. Differentially abundant proteins for each group comparison were determined at a threshold of 1.4-fold change. Differences in metabolite profiles were assessed via pairwise comparisons. A subset of differentially abundant proteins was validated via qRT-PCR and Western blotting. Results: Compared with the control, there were 90 proteins and 22 metabolites in the NEFA group, and 83 proteins and 29 metabolites in the NEFA + Chol. Compared with NEFA, there were 49 proteins and 17 metabolites in the NEFA + Chol group. Greater abundance of hexokinase-1 (HK1), fructose-bisphosphate aldolase (ALDOA), mitochondrial pyruvate carrier 1 (MPC1), and increased concentrations of lactate with high NEFA treatment alone suggested greater glycolytic and TCA cycle activity. Accumulation of triacylglycerol in the NEFA group was associated with lipotoxicity and markers of inflammation, such as greater abundance of prostaglandin reductase 1 (PTGR1), serious cell autophagy processes, such as greater abundance of cell division cycle 42 (CDC42), and NFκB-related proteins. Choline supplementation reduced TAG partly due to greater VLDL secretion driven by greater abundance of diacylglycerol acyltransferase (DGAT1), perilipin 3 (PLIN3), and apolipoprotein C-III (APOC3). In addition, a greater abundance of carnitine O-palmitoyltransferase 1b (CPT1B) with choline suggested enhanced mitochondrial β-oxidation. Activation of the CDC42/JNK pathway and ROS/NFκB axis-related proteins, along with depressed PI3K/AKT/RAC-related proteins, indicated enhanced mitochondrial autophagy in response to NEFA. Conclusions: Overall, data confirmed published effects of choline on TAG accumulation, VLDL secretion, and fatty acid oxidation, while highlighting negative effects of NEFA on the respiratory electron transport chain, autophagy, and inflammatory processes. Full article

The suckling phase is the critical window for rumen functional maturation, yet amino-acid-based interventions tailored to this stage remain scarce. L-citrulline (L-cit) bypasses hepatic first-pass metabolism, is converted to L-arginine peripherally, and resists ruminal microbial degradation, making it a candidate functional additive for early-life ruminants. This study evaluated whether dietary L-cit at 2 g·lamb⁻¹·d⁻¹ would improve rumen development and metabolic function in suckling Hu lambs. Twenty male Hu lambs were randomly assigned to a control (CON) or L-cit group (n = 10/group) and reared for 45 d (3 d adaptation + 42 d treatment). Growth and starter intake were assessed in all lambs; six lambs per group (n = 6) were subsequently slaughtered for rumen morphometry, gas chromatography–flame ionization detection (GC-FID) volatile fatty acid (VFA) quantification, 16S rRNA gene sequencing, and liquid chromatography–mass spectrometry (LC-MS) untargeted metabolomics. L-cit increased average daily starter intake by 25.96% (p = 0.036) and produced a 20.00% numerical but non-significant increase in average daily gain (ADG) (p = 0.203; Cohen’s d = 0.58). Rumen weight, volume, and papillary length, width, density, and epithelial thickness were all elevated (p < 0.05), whereas muscular thickness was unaffected (p = 0.162). Total VFA, acetate, propionate (+37.64%, p < 0.001), and butyrate were higher in the L-cit group; the molar proportion of propionate rose from 21.41% to 24.75%, and the acetate-to-propionate ratio declined from 2.90 to 2.44 (p = 0.005). Microbial richness (Chao1, Observed species) increased without altered evenness, and linear discriminant analysis effect size (LEfSe) identified L-cit-driven enrichment of propionate-generating and fiber-degrading genera, including Prevotellaceae_UCG-004, Ruminobacter, and the NK4A214_group. Of 539 differential metabolites (147 of which were annotated to the Kyoto Encyclopedia of Genes and Genomes (KEGG) database), KEGG enrichment highlighted linoleic acid metabolism and purine metabolism as the biologically interpretable targets. Microbiota–metabolite correlations linked L-cit-enriched genera to up-regulated metabolites such as adenine. Dietary L-cit at 2 g·lamb⁻¹·d⁻¹ enhances starter intake, promotes rumen epithelial development, promotes a shift toward enhanced propiogenic fermentation within an acetate-dominant profile, and remodels the microbiota–metabolome axis, supporting its application as a functional additive during the suckling phase of ruminants. Because epithelial barrier integrity, oxidative stress, and inflammatory markers were not directly measured, these findings should be interpreted as morphological and association-based evidence, and further functional validation is required. Full article

Grapevine branch and leaf silage (GBLS), a polyphenol-rich unconventional forage, exhibits antimicrobial and antioxidant properties that can benefit animal health and productivity. A total of 60 healthy six-month-old Kazakh rams (43.29 ± 4.55 kg, p > 0.05 for initial body weight among groups) were randomly assigned to three dietary groups, each consisting of four replicates with five rams per replicate. The control group (CK) was fed a basal diet based on whole-plant corn silage, whereas the experimental groups received diets in which 50% (GBLS50%) or 100% (GBLS100%) of the corn silage was replaced with GBLS. A 10-day adaptation period preceded the 90-day formal feeding trial. Results showed a significant quadratic response for average daily gain (ADG) and average daily feed intake (ADFI) across GBLS substitution rates (p < 0.05), with the 50% level yielding the highest values. Specifically, ADFI at the 50% replacement level was significantly higher than that of the control (p < 0.05), confirming an inverted U-shaped response with 50% as the optimal substitution rate. However, in-depth analysis of serum biochemical parameters revealed that GBLS supplementation significantly reduced serum concentrations of total cholesterol, triglycerides, urea nitrogen, interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), and malondialdehyde (MDA), while significantly increasing levels of immunoglobulins (IgA, IgM, IgG), superoxide dismutase (SOD), and catalase (CAT) (p < 0.05). Rumen fermentation analysis showed that the GBLS50% group had significantly lower concentrations of acetate, butyrate, and total volatile fatty acids (VFA) (p < 0.05). In the rumen microbiota study, no significant differences were observed in alpha or beta diversity or at the phylum level between groups (p > 0.05); however, the abundance of Lactobacillus gasseri was significantly reduced in the GBLS50% group (p < 0.05). Metabolomic profiling identified 43 significantly altered metabolites—27 upregulated (e.g., PE (18:1(9Z)/0:0) and 12,14-pentacosadiynoic acid) and 16 downregulated (e.g., deoxyadenosine). Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis highlighted purine metabolism as a significantly altered pathway (p < 0.05), providing insight into the potential metabolic mechanisms underlying the physiological effects of GBLS in rams. In conclusion, replacing 50% of whole-plant corn silage with grapevine branch and leaf silage improves growth performance trends and significantly enhances immunity and antioxidant capacity in Kazakh rams. Full article

This study investigated the effects of dietary nano-antimicrobial peptides (NAP) on the microbial communities and metabolic profiles in Tibetan sheep. Using 16S rRNA gene high-throughput sequencing and non-targeted metabolomics, the contents of the small intestine, rumen, and rectum were systematically analyzed in a control group (Group A) and a NAP-supplemented group (Group B). Multi-omics integration methods, including O2PLS and Pearson correlation analysis, were employed to explore the association between microbial communities and metabolites. Alpha and beta diversity analyses revealed significant differences (p < 0.05) in the microbial community structure of the small intestine between the two groups. In contrast, the rumen and rectal microbiota remained relatively stable, indicating that the regulatory effects of NAP on the intestinal microecology are site-specific. In the small intestine, NAP altered the composition of dominant functional microbiota and the abundance of taxa related to energy metabolism. Metabolomic analysis identified significant shifts in metabolic profiles, specifically within the bile acid, fatty acid, and phospholipid pathways (p < 0.05). Group A exhibited baseline steady-state characteristics (e.g., cholic acids and phospholipids), whereas Group B showed activation of unsaturated fatty acids and related metabolites. Multi-omics integration revealed a stable systematic association between intestinal microbial genera and metabolites. Specifically, bile acid and prostaglandin metabolites were negatively correlated with Firmicutes-related taxa. These findings suggest that NAP supplementation may contribute to maintaining host energy metabolism and intestinal homeostasis by regulating intestinal microecology. Full article

Deposition of three key 4-alkyl branched-chain fatty acids (KBCFA), including 4-methyloctanoic acid (MOA), 4-ethyloctanoic acid (EOA), and 4-methylnonanoic acid (MNA), causes the gamey flavor in sheep meat. This study integrated metagenomics and metabolomics to evaluate how Allium mongolicum Regel (AMR) supplementation (15 g/d) and rumen fluid transplantation (RFT) modulate rumen microbiota and hepatic metabolism to reduce KBCFA in lamb longissimus thoracis muscle. The experiment consisted of two phases. In Phase I, twelve 3-month-old male Dorper × Small Tailed Han sheep (25 ± 1 kg) were selected as the rumen donor group. These sheep were supplemented with 15 g/d/head of AMR powder in their basal diet until the end of the experiment. In Phase II, thirty 3-month-old male Dorper × Small Tailed Han sheep (23 ± 2 kg) were randomly assigned to one of three groups (n = 10 per group): the control group (STG), which was fed the basal diet and received a physiological saline transplant; the AMR group, which was fed the basal diet supplemented with 15 g/d/head of AMR powder and received a physiological saline transplant; and the rumen fluid transplant group (RTG), which was fed the basal diet and received a rumen fluid transplant from the donor group. Compared to the STG, results showed that the MOA, EOA, and MNA in the AMG decreased by 64.51%, 54.72%, and 49.34%, respectively. Similarly, the MOA, EOA, and MNA in the RTG were reduced by 63.13%, 56.17%, and 49.60%, respectively (p < 0.001). For the rumen metagenome, AMR enriched the genus Prevotella, while RFT increased Butyrivibrio. Hepatic metabolomics revealed a distinct shift where AMR elevated amino acid derivatives and RFT enhanced carnitine-related metabolites. These alterations indicate a potential metabolic shift associated with amino acid metabolism and mitochondrial β-oxidation, rather than lipid elongation. We postulate that this coordinated regulation across the rumen–liver–muscle axis may alter the availability of lipogenic precursors for KBCFA synthesis, ultimately contributing to improved meat flavor. 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

Yeast culture (YC), a complex functional feed additive containing fermentation metabolites, has demonstrated potential in dairy production systems. However, its mechanistic effects on rumen function and host metabolism in lactating dairy cattle warrant further investigation. This study evaluated the impacts of YC supplementation on production performance, systemic antioxidant status, and rumen function in late-lactation Holstein cows. Fourteen multiparous Holstein cows (body weight 655 ± 28 kg; days in milk 270.4 ± 1.6 d) were randomly allocated into two groups, a control group (CON, basal diet) and a YC-supplemented group (YC, basal diet + 50 g/d YC), in a 28-day feeding trial. YC supplementation significantly increased dry matter intake (p < 0.01), nutrient digestibility (p < 0.01 for DM, CP, EE, NDF, and ADF), and milk yield (p < 0.05) compared to CON. Systemic antioxidant capacity was enhanced, as evidenced by elevated serum superoxide dismutase activity (p < 0.01) and total antioxidant capacity (p < 0.05). Rumen fermentation was improved with higher concentrations of total volatile fatty acids (p < 0.01) and microbial protein (p < 0.01) and reduced ammonia nitrogen levels (p < 0.01). Macrogenomic analysis revealed a YC-mediated restructuring of the rumen microbiota, characterized by an increased relative abundance of Firmicutes and decreased Bacteroidota. Untargeted metabolomic profiling identified significant alterations in rumen metabolite profiles, with differential metabolites enriched in pyrimidine metabolism and vitamin digestion and absorption pathways. These results indicate that YC supplementation improves production performance in late-lactation dairy cows through multi-faceted mechanisms involving rumen microbial community modulation and metabolic pathway activation, ultimately enhancing nutrient utilization and metabolic efficiency. 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

This study aimed to investigate the effects of feeding high-moisture corn (HMC) on weight performance, serum immune and antioxidant indices, rumen fermentation, microbial community, and metabolomics in Kazakh rams. A total of 32 healthy Kazakh rams were randomly divided into a control group (CT, diet with only ordinary crushed corn) and an experimental group (GS, diet with 50% ordinary crushed corn + 50% HMC), following a 7-day adaptation period and a 120-day trial period. Results showed that the F/G was significantly lower in the GS group than in the CT group (p < 0.05). FBW, net weight gain and ADG increased by 4.58%, 8.69%, and 8.70%, respectively, while ADFI decreased by 7.04% (p > 0.05). Regarding serum immune indices, IgA in the GS group was significantly higher at 40 d (p < 0.01), and IgM was significantly higher at 40, 80, and 120 d (p < 0.05). For antioxidant indices, the SOD activity in the GS group was significantly higher than that in the CT group at 120 d (p < 0.01). The CAT activity in the GS group was significantly higher at 40, 80, and 120 d (p < 0.01). Among rumen fermentation parameters, the concentration of butyric acid in the GS group was significantly lower than in the CT group (p < 0.01). Microbial diversity analysis indicated no significant differences in Alpha- and Beta-diversity of rumen microorganisms between the two groups. However, the relative abundance of Firmicutes_A at the phylum level was significantly higher in the GS group (p < 0.05), and the abundance of Cryptobacteroides was significantly higher than in the CT group (p < 0.01). Rumen metabolomic analysis identified a total of 1357 differential metabolites, among which 1130 showed significant differences, with 459 upregulated and 671 downregulated. These were mainly enriched in pathways such as Glutathione metabolism, Beta-alanine metabolism, Sphingolipid metabolism, and lysine degradation. In conclusion, feeding HMC can improve feed conversion efficiency and weight performance in Kazakh rams, regulate the structure of dominant rumen microorganisms, and enhance immune and antioxidant capacities. 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

Slaughter performance is a critical economic trait that varies across breeds, yet the rumen metabolic mechanisms driving these phenotypic differences remain unclear. The study involved 30 healthy 12-month-old beef cattle, with 10 animals from each of the three breeds: Chinese Simmental (ST), Taihang Yun (TY), and Charolais (CL). The cattle were randomly assigned into three groups using a completely randomized design, and the average initial body weight was 549.78 ± 59.45 kg. A 130-day feeding trial (10-day pre-feeding period, 120-day main trial period) was conducted. By comparing the slaughter performance, relative organ weight, and rumen fluid metabolomic profiles, the study investigated breed-specific differences in meat quality and potential underlying metabolic patterns. The results showed that CL exhibited a superior carcass yield, with a significantly higher dressing percentage (62.38%, p = 0.013) and net meat percentage (56.54%, p = 0.028) than ST and TY, and a significantly lower backfat thickness (p = 0.006); ST had the highest proportion of premium cuts, relative to carcass weight (72.97%, p = 0.014), with prominent economic value, while TY had significantly higher weights of visceral organs, such as liver, kidney, small intestine and omasum, than CL (p < 0.05). Metabolomic analysis revealed that CL and ST had elevated levels of purine metabolism, nucleotide synthesis and cofactor biosynthesis compared to TY. In conclusion, CL and ST possess advantages in carcass yield supported by upregulated anabolic metabolism in the rumen, whereas TY prioritizes visceral organ development. These findings provide valuable insights into the physiological and metabolic divergences regulating the slaughter performance and regional adaptability across cattle breeds. Full article

The objective of this study was to investigate the relationships between ruminal microbial communities and carcass traits associated with adipose accumulation in two Tibetan sheep breeds—Gannan and Tianzhu. A total of twenty Tibetan sheep (ten from each breed) were slaughtered, and samples of ruminal contents along with carcass trait data were collected for analysis. Ruminal microbial DNA was analyzed by 16S rRNA gene sequencing, and correlations between microbial composition and carcass traits were examined using correlation analysis and one-way ANOVA. The results showed that marbling score (p = 0.001) and longissimus lipid content (p = 0.007) were positively correlated with the Chao1 richness index, indicating that individuals with higher intramuscular fat content had greater ruminal microbial species richness. At the phylum level, Rikenellaceae RC9 gut group, Ruminococcaceae NK4A214 group were negatively correlated (p ≤ 0.05) with the above fat traits, whereas the abundance of the bacterial family Ruminococcus 1 was positively correlated with marbling score (p = 0.002). Stratified analysis by marbling grade further revealed associations with microbial richness (p ≤ 0.063), diversity (p = 0.044), and Ruminococcus 1 abundance (p < 0.001). However, microbial metabolic pathway prediction showed no significant differences (p ≥ 0.05) between the high- and low-marbling groups. In addition, several microbial taxa were positively correlated (p ≤ 0.05) with rib fat thickness and yield grade. In summary, ruminal microbial composition was closely associated with variations in carcass fat traits. Notably, most of the bacterial taxa associated with intramuscular and subcutaneous fat deposition did not overlap, suggesting that microbial metabolites may regulate fat deposition by influencing distinct adipogenic pathways in the host. Full article