Search Results (129)

This study investigated the effects of supplementing rumen-protected lysine (RPL; 60 g/d) and methionine (RPM; 30 g/d) on nutrient digestibility, rumen fermentation, and microbial composition in 30 early-lactation Holstein dairy cows under both heat stress (HS) and non-heat stress (NHS) conditions. Cows were paired based on parity, milk yield, and body weight, and then assigned to one of two dietary treatments: the control group (CON), receiving the basal diet only, or the RPLM group, which received the basal diet supplemented with 60 g/d of RPL and 30 g/d of RPM (n = 15 per group). All animals underwent a transition from HS to NHS conditions during the experimental period, allowing for within-animal comparison across thermal environments. Results demonstrated that RPLM supplementation significantly improved the apparent digestibility of dry matter (DM), crude protein (CP), and neutral detergent fiber (NDF) (p < 0.05), with a significant treatment × environment interaction observed for DM digestibility (p < 0.01). Under HS conditions, RPLM reduced ruminal NH₃-N concentration (p < 0.05) and increased total volatile fatty acids (TVFA), acetate, and butyrate levels (p < 0.01), suggesting enhanced nitrogen utilization and energy metabolism. No significant effects were observed on ruminal pH or the acetate-to-propionate ratio. 16S rRNA sequencing revealed that RPLM supplementation increased the relative abundance of fiber-degrading and butyrate-producing taxa, including NK4A214_group, Christensenellaceae_R-7_group, norank_f__Muribaculaceae, and norank_f__F082. These microbial taxa exhibited strong positive correlations with DM and CP digestibility (p < 0.001). LEfSe analysis further confirmed their status as key microbial biomarkers in the RPLM-NHS group. Collectively, concurrent supplementation of RPL and RPM modulates the ruminal microbiota, alleviates HS-induced reductions in digestive efficiency, and enhances overall nutrient utilization in dairy cows. Full article

Ruminant production in the Chaco region relies on pastures and native forest foliage, whose nutritional value is poorly characterized and may be influenced by tannins. This study evaluated the in situ digestibility and in vitro ruminal fermentation of foliage from Prosopis affinis (PA), Prosopis nigra (PN), Acacia polyphylla (AP), Phyllostylon rhamnoides (PR), and Tabebuia nodosa (TN), incubated with or without polyethylene glycol (PEG) to assess the effects of tannin on gas production and nitrogen (N) compounds degradability. Foliage contained ≥17% crude protein (CP) and ≥40% fiber-bound N. Tannin concentration was >4% dry matter (DM) in PN and PA and <1% DM in PR, AP, and TN. In situ digestibility was ≤51% in all species except PR (73%; p < 0.05). Gas production was higher in PA, PR, and TN (p < 0.05), with no PEG effect. Methane production was not affected by tree species or PEG (p ≤ 0.277). Both species and PEG affected the effective N compounds degradability (END), with PEG increasing it in PN and AP (p < 0.05). Although foliage is high in CP, its digestibility is low; N is largely fiber-bound, and tannins may further limit END, factors to consider when including them in ruminant diets. Full article

Improving nitrogen efficiency in dairy cattle requires a better understanding of the dietary and ruminal factors that regulate nitrogen partitioning. This meta-analysis evaluated the effects of ruminal pH and dietary characteristics on microbial nitrogen (MN), non-microbial non-ammonia nitrogen (NANMN), and NAN flows to the small intestine in lactating cows. A dataset was assembled from 44 peer-reviewed in vivo studies (163 data points), with dietary intake and ruminal variables standardized across trials. Mixed linear models were developed for each N fraction, and the relative contribution of each predictor to the explained variance was assessed using semipartial coefficients of determination (pR²). Efficiency of microbial protein synthesis (EMPS), rumen undegraded protein intake (RUPI), and organic matter truly digested in the rumen (OMTDR) were the most relevant predictors of NANMN and NAN. Although the ruminal pH itself was not statistically significant in the models, the dietary components that influenced pH, starch concentration, physically effective fiber, and RUP supply were strongly associated with nitrogen flow profiles. Nitrogen utilization was not affected by ruminal pH, but rather by the combination of fermentable substrates and the supply of rumen-degradable and undegraded protein. Full article

The increasing demand for sustainable ruminant feeds has driven interest in the valorization of agro-industrial wastes. Artichoke wastes are attractive in the Mediterranean region due to their availability and richness in protein (CP) and fiber (NDF), but their high lignin (ADL) and tannin contents limit their nutritional value. This experiment was conducted using a completely randomized design with four treatments—control, ozone (O₃), exogenous fibrolytic enzyme (EFE), and O₃ + EFE—tested over six runs, each including three replicates per treatment. The study evaluated the effects of ozone (O₃) and exogenous fibrolytic enzyme (EFE) treatments, applied alone or in combination, on artichoke waste chemical composition, ruminal fermentation, microbial populations, enzyme activity, and degradability. Ozone pretreatment significantly reduced fiber fractions (NDF −10%, ADF −7%), ADL (−16%), and condensed tannins (−64%), while increasing CP (+13%) and non-fibrous carbohydrates (NFC +38%). These modifications enhanced ruminal bacterial populations (+29%) and fibrolytic enzyme activities (xylanase +21%, endoglucanase +19%, exoglucanase +10%), resulting in higher dry matter degradability (DMD +11%), fiber degradability (NDFD +14%), total volatile fatty acids (VFAs +13%), and a lower acetate-to-propionate ratio. EFEs alone showed negligible effects; however, when applied after ozone, further improvements were observed in NFCs (+21%), bacterial populations (+21%), enzyme activities (xylanase +11%, endoglucanase +10%), DMD (+8%), NDFD (+7%), and VFAs (+6%) compared to ozone alone. These findings demonstrate that O₃ pretreatment facilitates the enzymatic hydrolysis of lignocellulosic structures and enhances the effectiveness of EFEs, offering a sustainable and eco-efficient strategy for the bioconversion of artichoke wastes into high-value feed for ruminants, contributing to resource efficiency and circular bioeconomy development in livestock systems. Full article

Herbivorous animals rely on complex gastrointestinal systems and microbial communities to efficiently digest plant-based diets, extract nutrients, and maintain health. Recent advances in metagenomic technologies have enabled high-resolution, culture-independent analysis of gut microbiota composition, functional potential, and host–microbe interactions, providing insights into microbial diversity across the herbivore digestive tract. This review summarizes key findings on the gastrointestinal microbiota of herbivores, focusing on ruminant foregut and non-ruminant hindgut fermentation. Ruminants like cattle, sheep, and goats host microbiota enriched with fibrolytic and methanogenic microbes that facilitate fiber degradation and volatile fatty acid production, contributing significantly to energy balance. In contrast, non-ruminants such as horses and rabbits rely on hindgut fermentation, with distinct microbial taxa contributing to carbohydrate and protein breakdown. The review further explores how specific microbial taxa, including Prevotella, Fibrobacter, and Ruminococcus, correlate with improved feed efficiency and growth performance, particularly in ruminants. Additionally, the roles of probiotics, prebiotics, and symbiotics in modulating gut microbial composition and enhancing productivity are discussed. Despite significant advances, challenges remain in microbial sampling, functional annotation, and understanding the integration of microbiota with host physiology. The review emphasizes the potential of metagenomic insights in optimizing herbivore gut microbiota to improve feed efficiency, health, and sustainable livestock production. Full article

Climate change, feed shortages, and rising production costs highlight the need for alternative and sustainable forages for ruminants. This study aimed to evaluate the nutritional composition, in vitro ruminal fermentation, and methane emissions of Urtica dioica ecotypes originating from contrasting bioclimatic zones in Tunisia. Aerial parts of Urtica dioica were harvested at the early flowering stage from arid, semi-arid, and sub-humid regions. Samples were subjected to chemical composition in vitro ruminal fermentation to determine dry matter degradability (DMD), neutral detergent fiber degradability (NDFD), metabolizable energy (ME), and methane production. The results demonstrate that Urtica dioica is a promising protein-rich forage, with a stable crude protein content across ecotypes (18.58–20.97% of dry matter). In contrast, NDFD, DMD, ME, and methane emissions varied significantly according to origin. The arid ecotype, characterized by the highest fiber, ether extract, and polyphenol content, exhibited the lowest DMD (53% vs. 61% and 60%), NDFD (45% vs. 55% and 56%), and ME (7.2 vs. 8.6 and 9.0 MJ/kg dry matter) but produced the lowest methane emissions (38.8 vs. 53.2 and 74.2 mL CH₄/kg DMD) compared with the semi-arid and sub-humid ecotypes. The semi-arid and sub-humid ecotypes had comparable DMD, NDFD, and ME values; however, methane emissions were higher in the sub-humid ecotype. Overall, the semi-arid ecotype provided the most favorable balance between nutritive quality and environmental sustainability. These findings highlight the critical role of ecological origin in determining the feeding value and greenhouse gas footprint of Urtica dioica, providing a scientific basis for its potential use as a sustainable forage in ruminant feeding systems. Full article

Okara, a protein-rich byproduct of soymilk production, is highly perishable because of its high moisture content. This study evaluated the preservation and nutritional value of okara fermented by lactic acid bacteria for use in dairy cattle diets. Fermentation effectively reduced pH within 2 weeks and maintained quality for up to 6 weeks. However, aerobic exposure increased the concentration of ammonia, indicating a decline in stability. In vitro assessments revealed no significant differences in in vitro true dry matter digestibility, in vitro neutral detergent fiber digestibility, or gas production between fermented and fresh okara, although fermented okara had a higher concentration of ammonia nitrogen. In situ analysis revealed slightly lower dry matter effective degradability (ED) in fermented okara, but similar rumen-degradable and undegradable protein fractions. When fermented okara was used to replace soybean meal in total mixed rations, 25–50% inclusion-maintained digestibility and fermentation characteristics, with 25% replacement yielding the highest ED at a low ruminal passage rate (0.02 h⁻¹). Taken together, these results suggest that fermented okara can be strategically incorporated into dairy rations as a sustainable protein alternative, supporting both rumen function and bypass protein supply. Full article

This study evaluated the potential of utilizing Sesbania cannabina, produced during saline–alkali soil improvement, as a high-quality feed resource for ruminants. Mixed silages were prepared by combining S. cannabina and whole corn at ratios of 1:1 and 1:3, with or without a compound Lactobacillus (LAB) inoculant, and were assessed for fermentation quality, nutrient composition, ruminal degradation, intestinal digestibility, and energy value. Results: The addition of Lactobacillus (LAB) inoculants increased lactic acid content, crude protein effective degradability (CPED), gross energy (GE), and dry matter apparent digestibility (DMAD), while decreasing ammonia nitrogen (NH₃-N), acetic acid (AA), propionic acid (PA), neutral detergent fiber (NDF), acid detergent fiber (ADF), rumen undegradable protein (RUP), intestinal crude protein degradability (ICPD), and intestinal digestible crude protein (IDCP). Increasing the proportion of whole corn increased dry matter (DM) and gross energy (GE), while reducing crude protein (CP), NDF, ADF, Ash, rumen degradable protein (RDP), RUP, IDCP, and the effective ruminal degradability of NDF (NDFED) and ADF (ADFED). Overall, a 1:1 mixing ratio maximized S. cannabina utilization without compromising feeding value, and LAB inoculation ensured successful ensiling while enhancing nutrient utilization. Full article

The success of optimal ruminant production relies heavily on feed efficiency to deliver the necessary nutrients to animals. Nutritional deficiencies in livestock pose a significant challenge in regions experiencing prolonged fluctuations in resource availability and quality. In this context, the present study aimed to investigate the cumulative gas production (CGP) and in vitro degradability of silages made from spineless forage cactus (a native species) combined with high-fiber ingredients, to evaluate their viability as a sustainable, low-cost alternative to animal feed. The experiment involved ensiling spineless cactus genotypes with varying levels of sugarcane bagasse (0, 150, 300, 450, and 600 g/kg of dry matter) and a 1% urea–ammonium sulfate solution. The results indicated that for all genotypes studied, the CGP curves from silage composed solely of forage cactus differed significantly from those containing bagasse, which exhibited an initial phase characterized by little or no gas production. In vitro degradability was negatively influenced by the inclusion of bagasse at any level, resulting in decreased dry matter and organic matter degradability, as well as reduced CGP with increasing bagasse concentration. Therefore, the study demonstrated that the proposed combination of ingredients represents a promising sustainable feed supplement to enhance animal nutrition. Silage containing 150 g/kg of bagasse treated with urea offers a favorable balance between the energy required by rumen microflora and the benefits of fiber presence. Full article

Enhancing forage protein is key to sustainable ruminant nutrition. The nutritive value of Hedysarum coronarium L. was investigated by studying different preservation systems (fresh vs. dehydrated pellet vs. hay) (Exp. 1) and morphological fractions (flowers vs. leaves vs. stems) (Exp. 2). For the fresh and pelleted systems, two cuts were used. Proximately, total polyphenols and condensed tannins were detected. In vitro fermentation characteristics were studied by incubating samples with buffered sheep rumen fluid, estimating methane production by volatile fatty acids. Fresh and pelleted sulla were more nutritionally advantageous than hay, in terms of metabolizable energy and protein-to-fiber ratio. Pelleting at the beginning of flowering proved to be a suitable forage for sheep feeding due to protein (15.1% DM), metabolizable energy (9.64 MJ/kg DM), structural carbohydrates (39.5% DM), and total polyphenols (13.5 GAE g/kg DM) content. This cut showed an in vitro fermentation rate (9.86 mL/h), organic matter degradability (55.7%), and volatile fatty acids (87.3 mmoL/g) that were higher (p < 0.05) than hay. Flowers and leaves showed higher (p < 0.05) levels of secondary metabolites than stems as well as lower methane production. These results suggest the potential influence of these compounds in reducing rumen emissions. Dehydration and pelleting resulted in an effective preservation method for maintaining nutrients in sulla forage. Full article

Feed supplementation strategies are essential for optimizing cattle productivity, and the incorporation of non-conventional feed resources may reduce both production costs and environmental impact. This study evaluated the effects of pelletized protein concentrates (including Acacia farnesiana, A. schaffneri, and Agave duranguensis bagasse) on rumen fermentation parameters, microbial communities, and gas emissions. Fistulated bullocks received the concentrate daily, and ruminal contents were collected and filtered before and after supplementation to assess in vitro gas and methane production, pH, and microbial composition using high-throughput sequencing of 16S rRNA and mcrA amplicons. In addition, in situ degradability was evaluated during and after the supplementation period. Supplementation led to a significant (p < 0.05) reduction in degradability parameters and methane production, along with a marked decrease in the abundance of Methanobrevibacter and an increase in succinate-producing taxa. These effects were attributed to the enhanced levels of non-fiber carbohydrates, hemicellulose, crude protein, and the presence of bioactive secondary metabolites and methanol. Rumen microbiota composition was consistent with previously described core communities, and mcrA-based sequencing proved to be a valuable tool for targeted methanogen detection. Overall, the inclusion of non-conventional ingredients in protein concentrates may improve ruminal fermentation efficiency and contribute to methane mitigation in ruminants, although further in vivo trials on a larger scale are recommended. Full article

The aim of this study was to determine, through meta-analysis, the effects of malic acid/malate addition on ruminal and blood parameters and diet digestibility in cattle. The literature search was conducted in Web of Science, Science Direct, and Google Scholar using the terms “organic acids”, “malic acid”, “malate”, and “bovine”. The database was composed of papers published between 1980 and 2023. The average effect of malate/malic acid inclusion was calculated using the “DerSimonian and Laird” random effects model. Meta-regression and subgroup analyses were conducted to explore sources of heterogeneity. Overall, malic acid (MAC) addition did not significantly affect rumen pH (ES = 0.310, p = 0.17), but subgroup analysis showed that malate increased pH (ES = 1.420, p < 0.01). MAC increased rumen propionate (ES = 0.560, p < 0.01) and total volatile fatty acids (VFAs; ES = 0.508, p = 0.03), while reducing the acetate-to-propionate ratio (p < 0.01). Starch and NDF intake were significant covariates affecting pH and VFA-related variables. MAC improved total-tract digestibility of dry matter (DM; ES = 0.547, p ≤ 0.05), crude protein (CP; ES = 0.422, p ≤ 0.05), and acid detergent fiber (ADF; ES = 0.635, p ≤ 0.05). It increased glucose levels (Overall ES = 0.170, p = 0.05) and reduced NEFA (Overall ES = −0.404, p = 0.03). In conclusion, the effectiveness of MAC depends on its chemical form. Improvements in rumen pH, fiber degradation, and blood parameters suggest more efficient energy use and potential metabolic benefits. The influence of diet-related covariates suggests that the response to MAC may vary depending on the nutritional composition of the diet. Full article

Mixed silage can disrupt the girder structure of rape straw, and thus facilitate ruminal degradation. Further investigation is warranted to validate this observation in vivo. The objective of this study was to investigate the degradation kinetics and bacterial colonization of mixed silage during digestion using an in situ ruminal incubation technique. The experiment comprised two treatments: a mixture of rape straw and corn silage (control), and a mixed silage treatment of rape straw and whole crop corn (mixed silage). Three ruminally cannulated Holstein bulls were employed. Substrates were incubated for varying durations (4, 12, 24, 48, 72, 96, 120 and 216 h) to assess substrate degradation kinetics. Bacterial colonization were analyzed after 4- and 48-h incubation time. Mixed ensiling disrupted the fiber structure of rape straw, and thus had lower fiber content compared to the control, as NDF and ADF content ‌decreased by 55 g/kg (678 vs. 623 g/kg) and 27 g/kg (440 vs. 413 g/kg), respectively. Compared to the control group, ruminal DM disappearance of mixed silage significantly (p ≤ 0.05) increased from 315 to 366 g/kg (+16.2%) at an incubation time of 4 h, 552 to 638 g/kg (+15.6%) at 120 h, and 563 to 651 g/kg (+15.6%) at 216 h. Similarly, compared to the control group, NDF disappearance of mixed silage significantly (p ≤ 0.05) rose from 112 to 201 g/kg (+79.5%) at 4 h, 405 to 517 g/kg (+27.7%) at 120 h, and 429 to 532 g/kg (+24.0%) at 216 h. Compared to the control group, soluble and washout nutrient fractions (a) of DM or NDF fraction in mixed silage significantly (p ≤ 0.05) rose from 289 to 340 g/kg (+17.6%), potentially degradable fractions (b) of NDF increased from 310 to 370 g/kg (+19.4%), and the undegraded fraction of NDF (μNDF) decreased from 582 to 471 g/kg (−19.1%). Incubation time, apart from in the mixed ensiling treatment, altered the bacterial community. The study highlights that higher total potentially degradable fractions account for enhanced ruminal substrate degradation of mixed silage. Full article

Modified nano-clays, alone or combined with probiotics, may offer a novel and sustainable approach to improve ruminal fermentation and mitigate CH₄ emissions in high-fiber diets. This study evaluated the properties and effects of modified nano-bentonite (MNB), with or without yeast (Saccharomyces cerevisiae), compared to natural bentonite (NB) and monensin, using the in vitro gas production (GP) technique. The substrate used was a basal diet composed primarily of forage (Trifolium alexandrinum clover) in a 70:30 forage-to-concentrate ratio. The treatments were a control group receiving the basal diet without additives; a monensin-added diet containing 40 mg/kg of dry matter (DM); a yeast-added diet with Saccharomyces cerevisiae at 2 × 10⁸ CFU/g of DM; a NB clay-added diet at 5 g/kg of DM; and MNB diets added at two levels (0.5 g/kg of DM (MNB_Low) and 1 g/kg of DM (MNB_High)), with or without S. cerevisiae. MNB showed a smaller particle size and improved properties, such as higher conductivity, surface area, and cation exchange capacity, than NB. Sulfur and related functional groups were detected only in MNB. No differences were observed in total GP, while both the monensin diet and the MNB_High-with-yeast diet significantly reduced CH₄ emissions compared to the control (p < 0.05). The MNB_High-without-yeast combination significantly (p < 0.05) reduced hemicellulose degradation, as well as total protozoal counts, including Isotricha and Epidinium spp. (p < 0.05), compared to the control. Ammonia levels did not differ significantly among treatments, while NB and MNB_High diets tended to have (p = 0.063) the highest short-chain fatty acid (SCFA) concentrations. These findings suggest the potential modulatory effects of yeast and MNB on rumen fermentation dynamics and CH₄ mitigation. Full article

Acetate is naturally produced in the rumen through feed degradation and fermentation. It serves as a primary energy source for ruminants and as a key substrate for de novo fatty acid synthesis in the mammary gland. The interaction of exogenous acetate with different animal and dietary factors is an area of growing interest, as it may have significant implications for milk fat synthesis. This study aimed to assess the effect of two diet fermentability levels on the short-term response of lactation to acetate supplementation in dairy cows. Eight ruminally cannulated multiparous European Holstein cows were randomly assigned to treatments in a crossover design that tested the effect of diet fermentability, acetate supply, and their interaction. Using corn silage as the only forage source and a constant forage-to-concentrate ratio, high-fermentability (HF) and low-fermentability (LF) diets were formulated. Acetate supply was investigated by infusing ruminally 10 moles of sodium acetate/d (ACE) or an equimolar infusion of control (CON). Therefore, the treatments were as follows: LF + CON; LF + ACE; HF + CON; and HF + ACE. No interactions between acetate and diet fermentability were found on performance variables. Acetate infusion decreased dry matter intake (DMI), milk yield, and milk protein yield and content but did not affect milk fat yield; however, it increased milk fat concentration, and this response tended to be more pronounced in the HF diet. Acetate infusions increased plasma β-hydroxybutyrate in the HF diet, but not in the LF diet, and increased plasma non-esterified fatty acid, which was likely a lipolysis response to reduced DMI and decreased energy balance. This study demonstrates that acetate availability can be a constraint on mammary lipogenesis, even with adequate dietary fiber. Full article