Angus-based heifers (F0; n = 72; 14 to 15 mo; initial body weight [BW] = 380.4 ± 50.56 kg) were ranked by BW, bred via artificial insemination (AI) with female-sexed semen, and assigned to receive a basal diet (CON; n = 36) or the basal diet plus a vitamin and mineral supplement (VTM; n = 36) with the total mixed ration. Treatments were applied from breeding through calving, after which cow-calf pairs (n = 14 CON; n = 17 VTM) received a common diet. A subset of F1 heifers (n = 7 CON; n = 9 VTM) were bred via AI with female-sexed semen and evaluated from breeding through d 250 of gestation when pregnant heifers were slaughtered. Nutrient balance and energy metabolism were measured each trimester via apparent total tract digestibility and indirect calorimetry. Blood samples were collected each trimester and at harvest for hormone/metabolite analysis. Data were analyzed using the MIXED procedure of SAS with repeated measures where appropriate, with treatment, time, and interaction included as fixed effects and animal as the experimental unit. In F1 heifers, digestibility of dry matter, organic matter, neutral detergent fiber, acid detergent fiber, and N was not influenced by treatment (P ≥ 0.21) but decreased (P ≤ 0.03) as gestation advanced. Fecal energy (FE) losses, heat production (HP) as a percentage of gross energy intake, and retained energy (RE) were not affected by treatment (P ≥ 0.52); however, FE and HP increased (P ≤ 0.03) while RE decreased (P = 0.01) with advancing gestation. Circulating insulin concentration was greater (P < 0.01) in VTM heifers, whereas glucose decreased (P < 0.01) and non-esterified fatty acids and blood urea nitrogen increased (P ≤ 0.01) as gestation progressed. Body weight was greater (P < 0.01) in VTM heifers and at slaughter, VTM heifers tended (P ≤ 0.10) to have heavier carcasses and greater ribeye area than CON. The F1 CON heifers had heavier spleens relative to BW (P = 0.04) whereas other organs did not differ (P ≥ 0.17). In F2 fetuses, CON tended to have heavier reproductive tracts and spleens (P ≤ 0.10) with no other differences in organ weights (P ≥ 0.13), whereas VTM fetuses had greater (P = 0.01) blood glucose concentration. These results indicate that prenatal micronutrient supplementation programs growth and metabolic function across generations, with minimal effects on organ mass. Advancing gestation reduced efficiency of energy and nitrogen use, reflecting nutrient partitioning shifts supporting fetal growth.

Yeast culture has been widely used to modulate health and physiological functions in ruminants. However, its regulatory effects on hepatic metabolism remain incompletely understood. This study aimed to investigate the effects of compound yeast culture (CYC) on hepatic metabolic characteristics in lambs using untargeted metabolomics and to explore the underlying regulatory mechanisms. Eighteen weaned lambs were randomly assigned to three groups: a control group (Con) fed a basal total mixed ration (TMR), and two treatment groups supplemented with CYC at 40g/d (Group M) or 50g/d (Group Y) per head. Untargeted metabolomic analysis of lamb liver revealed that antioxidant-related metabolic pathways were significantly upregulated in Group M. In Group Y, in addition to the activation of antioxidant pathways, several energy metabolism-related pathways were downregulated. Biochemical validation further showed that the higher dose of CYC (50g/d per head) exerted a stronger regulatory effect on hepatic antioxidant capacity and energy metabolism. Overall, these findings suggest that CYC may regulate hepatic metabolism through coordinated modulation of antioxidant metabolism and energy utilization, thereby exerting protective metabolic effects on the lamb liver in a dose-dependent manner.

Understanding ruminal fermentation dynamics is essential for improving feed efficiency in ruminant nutrition. This study evaluated several nonlinear regression models to describe in vitro gas production kinetics in diets with different forage-to-concentrate ratios and buffer inclusion. Fermentation experiments were conducted using total mixed rations containing various concentrate levels, both with and without dietary buffers. Cumulative gas production data were fitted to exponential, logistic, Gompertz, and Michaelis–Menten models. Model performance was assessed using statistical goodness-of-fit criteria and the biological relevance of the estimated parameters. The results showed that buffer supplementation enhanced fermentation kinetics by stabilizing pH, increasing total gas production, and modifying volatile fatty acid profiles. Although no single model consistently outperformed others, model suitability depended on the specific diet–buffer combination. Sigmoidal models generally provided better fits for buffered diets, whereas exponential models were more accurate under high-concentrate, unbuffered conditions. These findings emphasize the importance of selecting context-specific models for analyzing ruminal fermentation data. The integration of in vitro gas production and nonlinear modeling offers a reliable approach to evaluate dietary strategies that improve nutrient utilization and feed efficiency in ruminant systems.

Validation and selection of nutritional markers to evaluate mixing quality in total mixed ration for dairy cows: Technical note.

Optimization of anaerobic fermentation and aerobic stability of total mixed ration via wet distiller's grains incorporation: Insights into clean recycling and nitrogen emissions control.

This study was conducted to evaluate the effects of supplementation strategies containing rumen-protected glucose (RPG) on growth performance, colonic fermentation characteristics, bacterial community structure, carcass traits, and meat quality in Simmental beef cattle. Thirty Simmental bulls with an initial body weight of 578.4±14.7 kg were randomly assigned to 3 dietary treatments for 90 d, with 10 animals per treatment. All animals received the same basal total mixed ration (TMR), to which the treatment supplements were added. The treatments were CON, unprotected glucose (150 g/d) plus coating fat (150 g/d); T1, RPG (100 g/d) plus unprotected glucose (100 g/d) and coating fat (100 g/d); and T2, RPG (300 g/d). Growth performance was recorded throughout the trial. At the end of the experiment, colonic digesta were collected for fermentation and bacterial community analyses, and carcass traits and meat quality were evaluated after slaughter. Compared with CON, both T1 and T2 had greater overall average daily gain (p<0.05), whereas feed efficiency differed marginally among treatments during the overall period (p = 0.049). In colonic digesta, propionate concentrations were higher in T1 and T2 than in CON, and butyrate concentration was higher in T2 than in CON and T1 (p<0.05). Alpha diversity was not affected by treatment; however, unweighted UniFrac-based PCoA showed differences in the overall colonic bacterial community structure among treatments.At the phylum and genus levels, several taxa showed nominal differences based on raw p values, but these were not retained after false discovery rate correction. Hot carcass weight and meat weight were greater in T1 and T2 than in CON (p<0.05). Intramuscular fat content was higher in T2 than in CON (p<0.05), whereas most other meat quality traits were not significantly affected. The supplementation strategies containing RPG improved overall growth performance and carcass output in Simmental beef cattle. They were also associated with higher colonic propionate and butyrate concentrations, indicating altered hindgut fermentation. The higher-RPG strategy (T2) was associated with greater intramuscular fat content.

The aim of this study was to evaluate the effect of the inclusion of tomato pomace silage (TPS) on feed intake, nutrient digestibility, blood parameters, immune response, milk yield, and milk nutritional composition in dairy cows. Sixteen Thai Holstein dairy cows with a mean body weight of 621±20 kg and 240±15 d in milk were randomly assigned to a completely randomized design. The TPS was added at 0%, 10%, 20%, and 30% dry matter (DM) in a fermented total mixed ration. Each cow was given the diet ad libitum. The nutrient intake was similar among treatments (p<0.05) except for ether extract intake, which increased linearly (p<0.01) with the addition of TPS. The inclusion of TPS at 20% and 30% linearly increased the digestibility of organic matter, crude protein, and ether extract (p≤0.01). The addition of TPS did not affect the blood chemicals or hematology except for monocytes, which increased cubically (p<0.05) when TPS were added. The immune function (IgA, IgM, and IgG) did not change with added TPS. Milk yield and milk composition did not change among treatments. The increasing levels of TPS slightly increased vitamin A and vitamin E in milk (p<0.01). The inclusion of TPS increased the oleic acid (C18:1 cis-9), linoleic acid (C18:2 cis-9,12+trans-9,12), and α-linolenic acid (C18:3 cis-9,12,15) in milk (p<0.05). The unsaturated fatty acids and monounsaturated fatty acids in milk increased linearly (p<0.05) in cows fed TPS, but TPS did not impact polyunsaturated fatty acids. The inclusion of 30% (on a DM basis) of TPS in the diets enhanced the digestibility of nutrients, milk vitamins, and milk fat (unsaturated fatty acids) without affecting the feed intake, blood parameters, or milk yield in late-lactating dairy cows.

Background: Dietary crude protein (CP) acts as a key nutritional factor that affects the growth performance and liver metabolism of fattening Hu sheep, with metabolizable energy (ME) representing a major confounding factor in CP-related responses. To isolate the specific effects of CP on liver metabolism and minimize energy-protein interactions, we standardized dietary ME at 9.4 MJ/kg dry matter. Methods: We then established three isoenergetic CP concentrations: 11.07%, 13.07%, and 15.11%. A total of ninety 4-month-old male Hu sheep (with an initial body weight of 27.09 ± 1.83 kg) were allocated at random to three dietary treatment groups, each containing 30 animals distributed across three replicate pens, and fed pelleted total mixed rations (PTMRs) for 75 days under pen conditions in southern Xinjiang. Exploratory combined transcriptomic and metabolomic profiling of liver tissue was conducted to characterize how graded CP levels modulate growth traits and hepatic metabolic pathways, thereby identifying the appropriate dietary CP level for efficient and sustainable fattening of Hu sheep in this region. Result: Results indicated that animals fed the 15.11% CP diet showed a significantly higher average daily gain (ADG) and cumulative weight gain compared with those fed 11.07% or 13.07% CP (p < 0.05). Exploratory multi-omics enrichment analysis demonstrated significant overrepresentation (p < 0.05) of differentially expressed genes and metabolites in key biological pathways-including bile secretion, AMP-activated protein kinase (AMPK) signaling, steroid biosynthesis, peroxisome proliferator-activated receptor (PPAR) signaling, and oxidative stress-related and oxidative phosphorylation. Correlation analyses characterized two hub genes-ATP6AP1 and LOC101119853-that were significantly and negatively correlated with ADG (p < 0.05), whereas two metabolites-calcidiol and ADP-displayed significant positive relationships with ADG (p < 0.05). Pathway-level comparisons further demonstrated that both the 13.07% vs. 15.11% CP and the 11.07% vs. 15.11% CP contrasts yielded significant enrichment in AMPK signaling and steroid biosynthesis. Notably, calcidiol and ADP both declined numerically in the 13.07% vs. 15.11% CP comparison, whereas only ADP reached statistical significance in the 11.07% vs. 15.11% CP contrast. Conclusions: Collectively, under an ME level of 9.4 MJ/kg, a dietary CP concentration of 15.11% contributes to favorable growth of 4-month-old fattening Hu sheep housed in pens in southern Xinjiang. This level is associated with improved growth performance and coordinated regulation of central hepatic regulatory networks-particularly those involved in energy homeostasis and steroidogenesis-thereby supporting metabolic stability without compromising animal health or production efficiency. These findings provide a preliminary molecular basis for precision protein nutrition in Hu sheep feeding systems and offer translational insights for optimizing ruminant nutrition under arid and semi-arid environmental constraints. All correlations indicate potential associations, not causal relationships.

The use of natural nutritional supplements has become increasingly common in livestock nutrition; nevertheless, because of its additional costs, a careful cost/benefit evaluation is essential to justify their practical application. The present study aimed to evaluate the effects of a blend of essential oils (EOs) included in the diet of dairy buffaloes on milk yield, chemical composition, milk urea nitrogen (MUN), and fatty acid profile. In addition, a detailed economic analysis was conducted to assess the overall profitability of this dietary strategy. A total of 98 buffaloes were enrolled in the trial and divided into two groups: a control group (C) and a treated group (T). The treated animals received 45 g/head/day of an essential oil blend in addition to a total mixed ration. An increase in milk yield was observed in the treated group at two sampling points, whereas no significant differences emerged in milk chemical composition. In contrast, MUN levels were consistently lower in the treated group throughout the trial. The fatty acid profile remained largely unchanged, except for higher levels of trans vaccenic acid (TVA) and eicosapentaenoic acid (EPA) in the treated animals. The economic analysis indicated that EO supplementation was financially advantageous for the farm. Overall, these findings suggest that essential oil blends may represent a promising nutritional strategy to improve production efficiency and milk quality in dairy buffalo. Future studies should investigate long-term effects, optimal dosages, and the mechanisms underlying the observed metabolic responses to support wider practical adoption.

Bioactive peptides (BP) have been investigated as potential functional feed additives due to their reported immunomodulatory and metabolic properties. This study evaluated the effects of dietary BP supplementation on growth performance, non-carcass components, serum biochemical profile and intestinal morphology in Texel lambs. Forty-five weaned lambs (31 castrated and 14 intact) were housed in pairs and fed for 58 days following a 20-day adaptation period. At the beginning of the experimental period, lambs averaged approximately 30kg body weight, reaching about 45kg at the end of the trial. Animals were assigned to three treatments: a control diet without BP and diets supplemented with 1-2g BP per animal per day. Lambs were fed a total mixed ration based on corn silage and concentrate. Performance parameters, non-carcass traits, serum biochemical variables and distal jejunum morphometry were assessed. Data were analyzed using linear mixed models in software R. Dietary BP supplementation did not affect final body weight, average daily gain, feed efficiency, non-carcass components or intestinal morphometric parameters (P > 0.05). A significant increase in serum albumin concentration was observed in BP-supplemented groups; however, no consistent changes were detected in other biochemical indicators. Under the conditions of this study, BP supplementation at practical inclusion levels did not improve growth performance or intestinal morphology in Texel lambs. Future studies should explore different dosages, feeding durations and stress conditions to further evaluate the potential benefits of BP supplementation in ruminants.

The objective was to evaluate the effects of Bacillus-based DFM supplementation during a 60-day feedlot receiving phase. Eighty-four Angus calves were ranked by initial body weight (BW = 280 ± 7.4 kg), age (233 ± 6 days), and sex (38 heifers and 46 steers), and allocated to 20 pens in a completely randomized design. Pens were randomly assigned to receive (i) a total mixed ration (TMR) plus 165 g of protein-mineral supplement + 3 g of a Bacillus-based DFM containing Bacillus licheniformis 809 and B. subtilis 810 (BAC; n = 10; 2.2 × 109 CFU of the mixture/g; Bovacillus, Novonesis, Lyngby, Denmark), and (ii) a TMR plus 165 g of protein-mineral supplement without DFM (CON; n = 10). Drylot pens were considered the experimental unit, with 4 to 5 calves per pen. Animals had free-choice access to the TMR offered daily at 0800 h. Feed samples were collected daily, and the refusals were removed weekly from the feed bunks. All samples were weighed, sampled, and dried to calculate dry matter intake (DMI). Calves shrunk BW was recorded on days 0 and 60 after 16 h fasting from water and feed. These values were used to calculate the average daily gain (ADG). Feed efficiency was calculated as the total experimental period BW gain divided by the total DMI for each pen. Blood samples were collected on days 0, 7, 14, 21, 28, 42, and 56 and analyzed for plasma concentrations of cortisol, nonesterified fatty acids (NEFA), β-hydroxybutyrate (BHBA), and glucose. Plasma samples from days 0, 7, 14, and 21 were also analyzed for haptoglobin concentrations. Hair samples were collected from the tail switch on days 0, 14, 28, and 42 and analyzed for cortisol concentrations. All data were analyzed using the MIXED procedure of SAS. Treatment was included as a fixed effect and pen(treatment) as a random effect; repeated-measures included time, treatment × time interaction, and calf(pen) as a random effect. There was a tendency for increased DMI in the BAC group compared to the CON group (P = 0.06), without any effect on the remaining performance parameters (P ≥ 0.50). A treatment × day interaction was observed for plasma cortisol concentration (P < 0.01), where animals from the CON group had increased cortisol levels on day 14. Mean plasma haptoglobin concentration was greater in CON compared to BAC cohorts (P = 0.03). Collectively, these findings suggest that Bacillus-based DFM enhanced feed intake and reduced plasma stress markers in feeder calves during a 60-day receiving program.

Fermented total mixed ration (FTMR) is an effective approach to preserve low-quality crop residues. This study investigated the effects of ensiling duration (0, 3, 5, 7, 15 and 30 days) on nutritional dynamics, fermentation quality, in vitro digestibility, and bacterial communities of FTMR containing corn stalk and broom sorghum straw at 50% moisture. After 30 d of ensiling, FTMR had the highest crude protein content, lowest neutral detergent fiber content, peak lactic acid concentration, stable low pH, undetectable butyric acid, and maximum in vitro NDF digestibility. Bacterial alpha diversity declined significantly during ensiling, and the community was dominated by Leuconostoc, Lactiplantibacillus, and Levilactobacillus. These results clarify the microbial regulatory mechanism of mixed-straw FTMR fermentation and support the efficient utilization of crop residues in ruminant production.

Large-scale monitoring of milk infrared-predicted blood biomarkers of stress resilience: effects of breed and dairy systems and their interactions.

Beet vinasse (VIN), a by-product of sugar beet processing, is rich in non-protein nitrogen (NPN), potassium, and prebiotic compounds, offering potential as a feed additive to enhance dairy cow performance while reducing environmental waste. This study investigates the effects of VIN supplementation at 0%, 1.5% (300g/day) or 3% (600g/day) on feed intake, feed efficiency (FE), milk production and composition, apparent nutrient digestibility, blood metabolites and ruminal fermentation in early-lactation Holstein dairy cows. Twenty-four Holstein dairy cows (15±3 days in milk, 30±2.9kg of milk/day) were used in a completely randomized design with three treatments: (1) control diet without beet VIN supplementation (0g VIN/cow/day, 0% VIN; V0); (2) diet supplemented with 300g VIN/cow/day (1.5% VIN; V1.5); and (3) diet supplemented with 600g VIN/cow/day (3% VIN; V3). VIN was top-dressed over the total mixed ration. The experiment included a 15-day adaptation period and a 30-day sampling period. Dry matter intake (DMI) was unaffected by treatments, whereas FE and milk yield increased linearly with increasing VIN levels. Fat-corrected milk (FCM), energy-corrected milk (ECM) and yields of milk fat, true protein, lactose and solids non-fat (SNF) increased linearly from V0 to V3. Milk fat percentage exhibited a quadratic response, with highest milk fat observed at the V1.5 level. True protein and concentrations of de novo and saturated fatty acids increased linearly with VIN inclusion. Apparent digestibility of dry matter, organic matter and crude protein improved linearly with increasing VIN levels. Ruminal pH, acetate proportion and acetate to propionate ratio increased linearly, whereas the proportions of valerate and isovalerate decreased linearly. Plasma globulin, total protein and blood urea nitrogen concentrations increased linearly, whereas plasma glucose concentration decreased linearly with increasing VIN. VIN supplementation at 1.5% or 3% enhances milk production, FE and nutrient digestibility in early-lactating cows without affecting DMI. However, increased plasma globulin may suggest a mild inflammatory response, necessitating further investigation. VIN supplementation at 1.5%-3% enhances nutrient digestibility, ruminal fermentation and production efficiency in early-lactating Holstein cows, likely due to its NPN and mineral content. However, without rumen microbial or immune response data, long-term safety and efficacy require further study. VIN offers a cost-effective, environmentally sustainable feed additive pending validation.

Optimizing ruminant diets and mitigating methane emissions using feed additives like yeast cell wall is of growing significance in animal nutrition. The present study aimed to evaluate the effects of varying roughage-to-concentrate (R:C) ratios and yeast cell wall (YCW) supplementation on rumen fermentation, gas kinetics and methane (CH4) production using an in vitro modified Hohenheim gas production (GP) system. In addition, in vitro digestibility (true, organic matter and neutral detergent fibre digestibility) was assessed using the ANKOM DaisyII incubator. Both systems employed the same rumen inoculum. A 3×2 factorial design was used, involving three different R:C ratios with or without YCW supplementation. The diets were formulated as total mixed rations, comprising roughages (wheat straw, vetch hay in equal proportions) and a concentrate mix at ratios of 30R:70C, 50R:50C and 70R:30C. A YCW supplement containing ∼40% crude protein, a minimum of 18% of mannan-oligosaccharides and 18% of β-glucans was added at 1.25g kg-1 diet. The results showed that cumulative (48h) and asymptotic GP did not differ among diets with varying R:C ratios. The 30R:70C diet showed a significantly higher gas rate constant and longer lag time than the other diets. YCW supplementation significantly reduced total and asymptotic GP and increased lag time. Significant R:C×YCW interactions were observed for GP and gas rate constant, as well as for 24h CH4 production. At 48h, CH4 output was similar for the 30R:70C and 50R:50C diets, while 70R:30C diet exhibited significantly lower CH4 production than the 30R:70C diet. Increasing roughage proportion reduced digestibility, while pH, volatile fatty acid (VFA) profiles and ammonia nitrogen (NH3-N) concentrations remained comparable across diets. YCW supplementation had no significant effect on diet digestibility, pH or VFA profile, although it tended to reduce NH3-N levels. YCW supplementation also reduced CH4 production, with greater effects observed in high roughage diets. Overall, YCW supplementation reduced total gas and CH4 volumes and influenced gas kinetics differently based on the R:C ratio. Further research is recommended to investigate the effects of YCW under different diet compositions, inclusion levels and shorter incubation periods.

Guanidinoacetic acid (GAA), a precursor of creatine, has emerged as one of the most promising supplements for ruminants in recent years. In its rumen-unprotected form, it is effective in different aspects of animal performance, but there are still no definitive studies on its ability to modulate reproductive responses. The objective of this study was to address this gap by investigating the action of GAA on ovarian function in sheep. Twenty-three sheep were allocated into three groups and fed a total mixed ration (TMR) for 23 days. The control group (n = 6) received the basal TMR diet; the GAA1 group (n = 7) received the same diet plus 0.9 g/kg DM of GAA daily; and the GAA2 group (n = 7) received 1.8 g/kg DM. Seven days after the start of supplementation, the sheep had their follicular wave synchronized with three prostaglandin doses administered every seven days. The GAA groups showed increased diet intake and reduced adipose deposits. GAA2 resulted in a higher number of follicles > 3 mm, greater intraovarian blood perfusion, and increased follicular diameter. At oocyte retrieval, the GAA groups showed lower peripheral glutathione peroxidase and, in oocytes, higher DCF and MT test intensities. In ovarian tissue, GAA2 showed higher expression of the AMH and CCND2 genes, while both GAA groups exhibited lower CYP19A1 and AKT1 transcript levels compared to the control. We conclude that the direct use of GAA in the diet of sheep effectively enhances ovarian function and oocyte metabolic modulation.

Omega-3 (ω-3) polyunsaturated fatty acids are well recognized for their potential to influence metabolic adaptation in dairy cows during the transition period. This study evaluated the effects of calcium salts enriched with ω-3 fatty acids, including α-linolenic acid and long-chain ω-3 fatty acids such as eicosapentaenoic and docosahexaenoic acids, on hepatic lipid metabolism-related proteins, oxidative stress biomarkers, and liver function in postpartum dairy cows. Prior to calving, cows received a total mixed ration supplemented with 0.400 kg dry matter (DM)/day of calcium salts derived from a flaxseed oil-fish oil mixture (60:40). After calving, cows were fed a partial mixed ration and received 0.650 kg DM/day of the same supplement mixed with a commercial concentrate during milking. Control cows received isoenergetic diets in which calcium salts were replaced with ground corn. Blood, urine, and liver samples were collected at -21 days relative to calving (used as a baseline covariate) and at +7, and +21 (±3) days postpartum, when treatment effects were evaluated. No differences were observed between treatments in conventional biochemical markers of liver function or hepatic triacylglycerol concentration. Plasma malondialdehyde concentrations were higher in ω-3-supplemented cows, whereas other oxidative stress parameters were not affected. Supplementation with ω-3 fatty acids was associated with changes in the abundance of selected hepatic proteins involved in fatty acid metabolism, including increased acyl-CoA oxidase 1 and 3-hydroxy-3-methylglutaryl-CoA synthase and reduced diacylglycerol O-acyltransferase 1 abundance, whereas carnitine palmitoyltransferase 1 and peroxisome proliferator-activated receptor alpha abundance were not affected. These findings indicate that ω-3-enriched calcium salts induce molecular adjustments in hepatic lipid metabolism during early lactation without evidence of adverse effects on liver function.

Methane is a major greenhouse gas with a global warming potential 28 times greater than that of carbon dioxide, making reduction of livestock emissions a critical challenge. Current mitigation strategies, such as feed management, chemical additives, and algae supplementation, face limitations related to safety, supply instability, and economic feasibility. To address these issues, we investigated the development of methanereducing feeds utilizing synbiotics. In a preliminary study, we evaluated the methane reduction potential of Komagataeibacter intermedius and Zygosaccharomyces parabailii (KZ), two SCOBY-derived strains, and identified prebiotics that promote their colonization. Genome-scale metabolic (GSM) models were constructed for three hydrogen-producing bacteria, five methanogens, and the KZ strain, and their metabolic networks were compared. Five prebiotics (glycerol, oleic acid, menaquinone-7, Gly-Leu, and Gly-Asn-L) were identified as substrates utilized by KZ but not by hydrogen-producing bacteria or methanogens. Coculture experiments confirmed that combined prebiotic treatment significantly enhanced KZ growth. In vitro rumen fermentation assays demonstrated reduced methane emissions in synbiotic-treated groups, with the combined prebiotic treatment resulting in the strongest inhibition. Based on these findings, a synbiotic-based fermented total mixed ration (FTMR) was developed. Synbiotic supplementation alleviated acidification, increased acetic acid production, and enriched bacterial and fungal populations. Microbial community analysis revealed higher abundance of lactic acid bacteria and non-Saccharomyces yeasts, indicating improved fermentation and enhanced feed quality. In conclusion, the synbiotic-based FTMR stabilized pH, altered organic acid profiles, and reshaped microbial communities, with synergistic interactions between lactic acid bacteria and yeast supporting a more stable fermentation environment. These results demonstrate that GSM modeling is effective for designing synbiotic-based feeds and that the newly developed synbiotic FTMR improves fermentation quality. Notably, this study focused on prebiotic identification, synbiotic formulation, are fermentation characterization; direct evaluation of the methane reduction efficacy of FTMR under in vitro and in vivo conditions remains a subject for future investigation.

BACKGROUND: Previous study has found that gastrointestinal tract (GIT) bacteria are involved in the regulation of medium-chain fatty acid triglycerides (MCTs) on the improvement of growth performance in finishing bulls. At present, the effects of MCT on GIT fungi of finishing bulls has not been reported, whether fungi are also involved in the regulation of the growth performance is still unknown. The objective of this study was to investigate GIT fungal composition and diversity of finishing bulls fed different MCT. RESULTS: The study employed four ruminally fistulated Yanbian cattle (18-month-old bulls) in a 4 × 4 Latin square design, and were divided into four treatment groups: a control group (CON) receiving a basal total mixed ration (TMR), and three experimental groups (C8, C10, and C12) supplemented with 60 g/bull/day of glycerol monocaprylin (GMC), glycerol monodecanoate (GMD), and glycerol monolaurate (GML), respectively. At the end of each experimental period, rumen fluid, rumen digesta, and rectum feces were collected for ITS sequencing. In the rumen digesta, the relative abundance of o_Eurotiales and f_Aspergillaceae in the C12 group were significantly increased compared with the CON, C8, and C10 groups (P = 0.038 and 0.028, respectively), while in the rumen fluid, the relative abundance of g_Cyllamyces in the C10 group was significantly increased compared with the CON, C8, and C12 groups (P = 0.036). CONCLUSIONS: There were some differences in the composition and diversity of fungi among different samples and different MCT treatment groups in finishing bulls. Moreover, based on correlation analysis, it is found that GIT fungi may also be involved in the regulation of GMC/GMD/GML on the improvement of feed intake, antioxidant status or nutrient digestibility in finishing bulls.

The intensive lamb rearing and finishing systems are usually based on nutritionally balanced concentrate-based rations. However, the inclusion of feed additives is often necessary to avoid possible disturbances of digestibility. Artificial saliva plays an important role in ruminal buffering, improving the digestibility of the feed under conditions where natural saliva production may be insufficient. The study aimed to evaluate the effects of dietary artificial saliva (AS) on the total mixed ration (TMR) on lambs' growth performance, carcass characteristics and the efficacy of ruminal fermentation. Forty-five male Naemi lambs (mean body weight of 23 ± 1.8 kg) were randomly assigned to five experimental groups (n = 9 per group) and kept in complete confinement with water and adlibitum feeding. During the 84-day feeding period, animals received isonitrogenous and isoenergetic TMRs that vary in AS inclusion by level: T0 (0% AS), T2 (1.5% AS), T3 (3.0% AS), T4 (4.5% AS), and T5 (6% AS). No significant differences (p > 0.05) were observed in the overall performance parameters. However, lambs fed the control diet (0% AS) had a higher body weight (BW), average daily gain (ADG), and feed intake (FI) than those receiving AS supplementation (p < 0.01). Ruminal pH measured 3 h after feeding and at slaughter remained comparatively stable in lambs fed 3% and 4.5% AS treatments, whereas it declined to 5.21 in the control group. Dietary inclusion of AS at 4.5% significantly increased (p < 0.05 < 0.05) the molar proportions of butyric acid, iso-valeric acid, and valeric acid in ruminal fluid while other levels of artificial saliva were associated with reduced concentrations of volatile fatty acids (VFAs). In conclusion, AS effectively functioned as a buffering agent, enhancing dietary safety without adverse health effects.