Search Results (85)

This study evaluated the effects of replacing SBM with CWYWEP on in vitro rumen fermentation, nutrient degradability, and gas production kinetics. Citric waste was co-fermented with yeast waste and a multi-enzyme complex for 14 days, then sun-dried and pelleted. The final CWYWEP product contained 50.4% crude protein (DM basis). A completely randomized design tested seven diets in which SBM was replaced by CWYWEP or non-enzymatic citric waste–yeast waste pellets (CWYWP) at 0%, 33%, 66%, or 100% inclusion. Replacing SBM with CWYWEP significantly increased cumulative gas production at 96 h, with the 100% CWYWEP group achieving 93.7 mL/0.5 g DM—a 14% increase over the control (p < 0.01). Microbial lag time was reduced to 0.17 h vs. 0.28 h in the control (p < 0.05), suggesting faster microbial colonization. The highest in vitro DM degradability (IVDMD) at 48 h was observed in the 100% CWYWEP group (64.5%), outperforming both the SBM control and all CWYWP treatments (p < 0.01). Notably, CWYWEP increased total volatile fatty acids by 5% at 4 h and propionate by 9% at 2 h, while reducing methane production by 5% (p < 0.05). Other parameters, including pH, ammonia nitrogen, organic matter digestibility, and protozoal counts, were unaffected (p > 0.05). In contrast, CWYWP without enzymes showed minimal improvement. These findings indicate that CWYWEP is a promising high-protein alternative to SBM, enhancing fermentation efficiency and reducing methane under in vitro conditions. Further in vivo studies are warranted to validate these effects. Full article

While the Ankom RF system facilitates efficient high-throughput in vitro fermentation studies, its high cost and limited flexibility constrain its broader applicability. To address these limitations, we developed and validated a low-cost, modular gas monitoring system (FerME), assembled from commercially available components. To evaluate its performance and reproducibility relative to the Ankom RF system (Ankom Technology, Macedon, NY, USA), in vitro rumen fermentation experiments were conducted under strictly controlled and identical conditions. Whole rumen contents were collected approximately 2 h post-feeding from individual mid- or late-lactation dairy cows and immediately transported to the laboratory. Each fermenter received 50 mL of processed rumen fluid, 100 mL of anaerobically prepared artificial saliva buffer, and 1.2 g of the donor cow’s diet. Bottles were sealed with the respective system’s pressure sensors, flushed with CO₂, and incubated in a 50 L water bath maintained at 39 °C. FerME (New Taipei City, Taiwan) and Ankom RF fermenters were placed side-by-side to ensure uniform thermal conditions. To assess the effect of filter bag use, an additional trial employed Ankom F57 filter bags (Ankom Technology, Macedon, NY, USA; 25 μm pore size). Trial 1 revealed no significant differences in cumulative gas production, volatile fatty acids (VFAs), NH₃-N, or pH between systems (p > 0.05). However, the use of filter bags reduced gas output and increased propionate concentrations (p < 0.05). Trial 2, which employed filter bags in both systems, confirmed comparable results, with the FerME system demonstrating improved precision (CV: 4.8% vs. 13.2%). Gas composition (CH₄ + CO₂: 76–82%) and fermentation parameters remained consistent across systems (p > 0.05). Importantly, with 12 pressure sensors, the total cost of FerME was about half that of the Ankom RF system. Collectively, these findings demonstrate that FerME is a reliable, low-cost alternative for real-time rumen fermentation monitoring and could be suitable for studies in animal nutrition, methane mitigation, and related applications. 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

Pelagic sargassum arriving in the Mexican Caribbean is a mixture of brown macroalgae containing polysaccharides, minerals, and secondary metabolites with potential in ruminant diets. The objective of the present study was to evaluate the effect of the inclusion of sargassum in integral diets (ID) on in vitro fermentation characteristics. A completely randomized design was used. The treatments were different levels of sargassum (ICD: 0%, ID10: 10%, ID20: 20% and ID30: 30%) added to a basal substrate (a mixture of Pennisetum purpureum Vc. CT-115 hay, corn, soybean, and molasses). Rumen fluid was obtained from five male lambs with a body weight of 40 ± 3 kg. In vitro gas production (IVGP) as well as dry matter degradability (DMD) and organic matter degradability (DOM) increased linearly (p < 0.0001) as the proportion of sargassum increased at 24, 48, and 72 h. Rumen fluid pH decreased (p < 0.05) with 30% inclusion at 48 h, while protozoan concentration was similar (p > 0.05) in all treatments with respect to the control at all evaluation times. These results indicate that the inclusion of pelagic sargassum in integral concentrated diets improves fermentative parameters, and its inclusion in diets for ruminants is feasible. This opens up a window of opportunity for its study as a novel additive or unconventional supplement. However, in vivo studies are necessary to rule out harmful effects on animal health and performance. Full article

This study evaluated the effects of feedstuffs and additives in dairy cow rations on rumen methane production and nitrate content in groundwater. Two basal rations and their supplements were analyzed in regard to proximate parameters, and an in vitro rumen fermentation system assessed methane release and nitrate levels over 72 h. Supplementing dairy cow rations with Brassica rapa (BR) boosted the ether extract content, while silage produced the highest amount of methane. Rapidly degrading substrates like BR and ground maize produced methane faster, but in smaller amounts, than straw and silage. BR, Opuntia ficus-indica (OFI), and Posidonia oceanica (PO)-supplemented rations had mixed effects; PO reduced the methane yield, while OFI increased methane production rates. BR-supplemented rations had the lowest nitrate levels, making it suitable for anaerobic digestion. The multivariate analysis showed strong correlations between crude protein, dry matter, and ash, while high-nitrate substrates inhibited methane production, supporting the literature on the role of nitrates in reducing methanogenesis. These results emphasize the need to balance nutrient composition and methane mitigation strategies in dairy cow ration formulations. Full article

The objective of this study is to isolate, identify, and describe rumen yeast strains and assess their probiotic potentials and effects on ruminal fermentation in vitro. Yeasts were isolated from ruminal fluids, yielding 59 strains from nine distinct species. A number of tests were conducted to assess their anaerobic traits, growth rate, acid tolerance, and lactate utilization ability, and a second screening in fresh ruminal fluid to evaluate in vitro pH and acid accumulation was conducted. The probiotic yeast Candida rugosa (NJ-5) was selected for in vitro culture studies on rumen fermentation. Finally, Candida rugosa (NJ-5) with good probiotic characteristics was chosen to investigate its effects on ruminal fermentation in vitro. The batch culture technique was used to explore the effects of Candida rugosa (NJ-5) yeast culture on rumen fermentation parameters. By altering the fermentation substrate to a concentrate-to-roughage ratio of 70:30, which simulated a high-concentration diet. The CON, LYC, MYC, and HYC groups were supplemented with 0%, 1%, 2%, and 5% Candida rugosa (NJ-5) yeast culture (dry matter basis), respectively. The pH value and volatile fatty acid (VFA) contents were determined at 6, 12, and 24 h after fermentation. The results showed that adding Candida rugosa (NJ-5) yeast culture successfully modulated in vitro rumen fermentation. Compared to the CON group, HYC had a significantly mitigated reduction in pH in fermentation, resulting in a significant increase in total VFAs and acetate levels (p < 0.05). Additionally, 16S rRNA sequencing revealed that Candida rugosa (NJ-5) yeast culture supplementation did not significantly alter ruminal bacterial alpha diversity (p > 0.05). At the phylum and genus taxonomic levels, Candida rugosa (NJ-5) yeast culture addition increased the relative abundance of several functionally important bacterial groups in the rumen microbial community. Compared to the CON group, the HYC group concurrently had an increased abundance of Desulfobacterota, Christensenellaceae_R-7_group, F082, and Ruminococcus (p < 0.05) but a significantly reduced abundance of Cyanobacteria, Bdellovibrionota, Succinivibrionaceae_UCG-002, Enterobacter, and Succinivibrio (p < 0.05). The in vitro fermentation experiment demonstrated that the optimal dry matter supplementation of Candida rugosa (NJ-5) into the basal diet was 5%, which could be effective for maintaining ruminal fermentation stability when ruminants were fed a high-concentrate diet. This study provides empirical support for the use of yeast as a nutritional supplement in ruminant livestock management, as well as a theoretical underpinning for further animal research. Full article

This study aimed to determine the optimal supplementation level of sodium humate (SH) for improving rumen fermentation efficiency in vitro. Using rumen fluid from four donor ewes with three experimental replicates per treatment, we evaluated a basal diet supplemented with SH at 0 (control), 0.5 (SH0.5), 1 (SH1), and 2 (SH2) g/kg dry matter. The results of this study revealed that after 12 h of incubation, compared to the control group, the SH0.5 group significantly decreased gas production (GP) by −11.66% (p < 0.01). There were no significant differences in pH values, bacterial crude protein (BCP) content, and ammonia nitrogen (NH₃-N) concentration among the groups (p > 0.05). After 24 h of incubation, no significant differences in pH values were observed among the groups (p > 0.05). The SH1 group exhibited significantly higher BCP content compared to other treatments (p < 0.05), concomitant with a marked reduction in NH₃-N concentration (p < 0.01). Compared to the control group, GP in the SH1 group increased significantly by 7.16%, and a significant increase of 5.43% (p < 0.05), while it decreased significantly by −9.96% in the SH0.5 group (p < 0.01). However, no significant differences in volatile fatty acids were observed among the groups after either 12 or 24 h of fermentation. The addition of 1 g/kg SH altered the composition of the rumen bacterial community, which was indicated by the increased relative abundances of Prevotella, Anaerovibrio, and Saccharofermentans and the decreased relative abundances of Actinobacteriota, Lachnospiraceae_NK3A20_group, and [Ruminococcus]_gauvreauii_group (p < 0.05). Furthermore, Anaerovibrio was negatively correlated with NH₃-N and positively correlated with gas production, while [Ruminococcus]_gauvreauii_group was negatively correlated with gas production. The study indicates that the addition of 1 g/kg SH optimizes rumen fermentation efficiency and improves nutrient utilization by modulating the structure and composition of the bacterial community, thus serving as an effective additive for enhancing rumen fermentation and feed utilization in ruminants. Full article

An in vitro and an in vivo study were conducted to investigate the effects of a blend of cinnamaldehyde, eugenol, and capsicum oleoresin (CEC) on rumen fermentation parameters, animal performance, and methane (CH₄) emissions in dairy cows. Continuous culture fermenters (CCF) were utilized to test one of two treatments: (1) CON; no supplementation and (2) CEC supplemented at 0.0125 g/d. The basal diet consisted of grass hay and concentrate (50:50). Supplementation with CEC increased (p < 0.01) total volatile fatty acids (VFA; mM) and decreased (p = 0.02) CH₄ concentration compared with CON in vitro. Additionally, protozoa abundance tended (p = 0.07) to decrease in CEC compared with CON. The in vivo experiment utilized forty Holstein-Friesian dairy cows (32% primiparous and 68% multiparous) averaging 163 ± 48 days in milk (DIM) and 38 ± 6.2 kg/d of milk yield (MY). Cows were blocked by parity and randomly assigned to one of two treatments: (1) CON; no supplementation and (2) CEC supplemented at 1.2 g/cow/d. The basal diet consisted of grass hay and concentrate (40:60). Individual CH₄ emissions were recorded using the sniffer technique. Dry matter intake (DMI) and eating rate were increased (p < 0.01; 3.6% and 5.2%, respectively), while feed efficiency decreased (p < 0.05) in CEC compared with CON. Additionally, CEC decreased (p = 0.02) CH₄ yield by 16.4% and tended to reduce daily CH₄ production (p = 0.09) and CH₄ intensity (p = 0.08) by 13.4% and 14.0%, respectively. Supplementing CEC decreased CH₄ concentration in vitro and CH₄ yield in vivo without negatively impacting performance parameters. Full article

The consumption of forages high in slow-degradable carbohydrates by dairy cattle leads to greater ruminal acetate production, which benefits milk fat content. Although tropical grasses are typically rich in fibrous materials, the milk fat content of dairy cows in Southeast Asia is low. Here, we investigate the effects of the species and harvest time of three common tropical grasses (Guinea, King, and Mulato II) harvested at three instances (early, normal, late) on in sacco degradation kinetics and in vitro gas production (IVGP) characteristics. Grass samples were subjected to (1) chemical analysis, (2) a fully automated in vitro gas recording system using rumen fluid to measure fermentation characteristics over 72 h, and (3) in sacco degradation using the nylon bag technique, employing seven incubation times up to 336 h. Forage quality decreased with maturity, as reflected in changes to digestibility and fiber content. Overall, early harvested grasses yielded the highest total gas production (311 ± 12.5 mL/g OM) followed by normal (300 ± 45.7 mL/g OM) and late (273 ± 19.5 mL/g OM) harvested grasses. The in vitro fermentable fraction (A1 + A2) was the highest for early harvested grasses, with the A2 parameter, relevant for milk fat content, being the highest for Guinea (81.6% A2/(A1 + A2)) and the lowest for King grass (71.0% A2/(A1 + A2)). Consequently, early harvested Guinea had the longest incubation times (10.5 h) and lowest fermentation rates (Rmax2 = 12.8 mL/g OM/h). Regression analysis showed relationships between NDF content and degradability. Harvesting tropical grass earlier than customarily practiced enhanced forage quality and ruminal degradability. Of the three grasses studied, each at three levels of maturity, early harvested Guinea grass was the most promising candidate for improving milk fat content in Southeast Asian dairy cows. This grass showed a high fermentable OM content, with a large proportion of slow-degradable carbohydrates. Full article

This study investigated the feasibility of incorporating Chenopodium album L. (CAL) into ruminant feed ingredients through evaluating the effects of harvest time and substitution levels on in vitro rumen fermentation. In the first phase, a sole-substrate experiment was conducted using CAL harvested from June to August, analyzing its chemical composition and total saponins content. The impact of harvest time on fermentation parameters was assessed with CAL as the sole substrate. The second phase involved a mixed-substrate experiment using an early-fattening Hanwoo diet (30% rice straw and 70% concentrate), where increasing proportions of CAL (control: 0%, T1: 5%, T2: 10%, T3: 15%, and T4: 20%) replaced rice straw. Seasonal variations in CAL composition influenced the fermentation characteristics. CAL harvested in July exhibited higher fermentability, with total volatile fatty acids (TVFAs) reaching 103.87 mM at 72 h. In contrast, CAL harvested in August showed lower fermentability and digestibility. However, August-harvested CAL was selected for the subsequent experiment, as it provided a more practical balance of sufficient biomass yield and a higher saponins concentration, aligned with the study’s methane mitigation objectives, while also exhibiting a fiber composition comparable to that of rice straw. We hypothesized that the saponins in CAL contribute to methane reductions. Supplementation with 15% of CAL significantly reduced methane production per gram of inoculated and digested dry matter (p < 0.05), likely due to differences in crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), and saponins content. However, despite having the lowest fiber content, T4 (20% CAL) exhibited the lowest in vitro dry matter digestibility (IVDMD), suggesting that factors such as saponins, CAL’s chemical composition, or microbial shifts may have hindered digestibility. Ammonia–nitrogen production increased from 0 to 3 h, but it continuously decreased between 3 and 9 h due to microbial growth and nitrogen assimilation, as microbes incorporate ammonia into their biomass (p < 0.05). Fermentation characteristics further revealed that the acetate-to-propionate (A/P) ratio decreased with increasing CAL levels, with T4 showing the lowest ratio (1.55 at 72 h), confirming a shift toward propionate-based fermentation. Notably, T2 (10% CAL) showed an optimized fermentation efficiency, producing the highest TVFA concentration at 24 h (98.28 mM). These findings highlight the potential for using CAL as a functional feed ingredient, with moderate substitution levels (10–15%) enhancing fermentation efficiency while reducing methane production. Full article

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

Yeast culture can improve ruminant health and reduce economic losses in intensive farming, but as a non-standardized product in China, its quality and efficacy vary significantly. In this study, a self-developed yeast culture was compared with a commercially available product using in vitro rumen fermentation and amplicon-based high-throughput sequencing to evaluate its effects on rumen fermentation parameters, microbial diversities, and community compositions in Hu sheep. The aim was to validate the efficacy and mechanisms of the self-developed yeast culture, produced with simplified raw materials and processes, on rumen function. The experiment was divided into four groups. In each 60 mL fermentation solution, the following treatments were added: 0.00 g high-concentrate diet (CK1 group, blank control), 0.40 g high-concentrate diet (CK2 group, basal diet control), 0.40 g high-concentrate diet supplemented with 5% XP yeast culture (XP group), and 0.40 g high-concentrate diet supplemented with 5% YC yeast culture (YC group). Gas production was measured every 4 h during fermentation. At the end of fermentation, pH, ammonia nitrogen, microbial protein, volatile fatty acids, and ruminal microbiota were determined. The results demonstrated the following. Compared to the CK2 group, both the XP and YC groups exhibited a significant increase (p < 0.05) in cumulative gas production and microbial protein content, while a significant decrease (p < 0.05) was observed in acetic acid content and the acetate-to-propionate ratio. The microbial protein content in the YC group was significantly higher (p < 0.05) than that in the XP group. Additionally, the content of valeric acid and isobutyric acid in the XP group was significantly higher (p < 0.05) compared to the other groups. The microbial community sequencing results revealed that the addition of yeast culture did not affect the alpha diversity index of rumen bacteria (p > 0.05); however, the addition of XP significantly reduced (p < 0.05) the richness of rumen fungal communities. At the phylum and genus levels, the relative abundance of multiple functional bacteria improved after adding YC. In summary, under the conditions of in vitro rumen fermentation with high-concentrate diets, adding 5% XP and YC yeast cultures both promoted rumen fermentation. The rumen fermentation type changed from the acetic acid type to the propionic acid type, which regulated rumen microbial composition and thereby improved dietary digestion efficiency. Notably, YC significantly increased the relative abundance of functional microbial communities compared to XP. These findings provide a theoretical and practical foundation for optimizing the large-scale breeding of Hu sheep. Full article

Alfalfa silage has a high proportion of rumen-degradable protein content. Increasing dietary rumen-degradable starch (RDS) can enhance ruminal microbial protein synthesis. This study was conducted to investigate the influence of RDS levels in substrates with alfalfa silage on in vitro rumen fermentation and nitrogen (N) utilization. Rumen fluid was collected and dispensed into anaerobic fermentation bottles, each containing 1 g of substrate and 60 mL of rumen fluid–buffer mixture. The substrate was composed of 40% alfalfa silage and five different RDS levels: 14.85% RDS, 16.40% RDS, 18.67% RDS, 20.21% RDS, and 21.62% RDS. For each RDS level, three replicates were prepared. Each substrate was then incubated at 39 °C for 3, 6, 12, and 24 h. After incubation, the following parameters were measured: gas production, pH, α-amylase activity, ammonia nitrogen (NH₃-N), bacterial protein (BCP), and short-chain fatty acid (SCFA) concentrations were measured. Total gas production increased linearly with increasing RDS levels from 3 to 10 h of incubation (p < 0.01), with no difference observed among five levels after 11 h. At 3 h of incubation, pH decreased linearly with increasing RDS levels (p < 0.05). BCP concentrations and α-amylase activity increased linearly or quadratically with increasing RDS levels (p < 0.01), while the R4 group had the highest concentrations of BCP and the R5 group had the highest activity of α-amylase (p < 0.01). At 6 h of incubation, the NH₃-N concentration decreased linearly or quadratically with increasing RDS levels (p < 0.05), and the α-amylase activity, acetate, propionate, and total SCFA concentrations increased linearly (p < 0.01). The R4 group had the highest activity of α-amylase (p < 0.01), and the R5 group had the highest concentrations of acetate (p < 0.05) and propionate (p < 0.01). At 12 h of incubation, BCP, NH₃-N, and propionate concentrations, as well as α-amylase activity, increased linearly or quadratically with increasing RDS levels (p < 0.05). At 24 h of incubation, the α-amylase activity increased linearly with increasing RDS levels (p < 0.05). The highest multiple-factor associative effects index was observed in the 20.21% RDS substrate, indicating that an RDS level of 20.21% in the alfalfa silage substrate resulted in a desirable rumen N utilization. Full article

The increase in global temperatures over the past few decades due to greenhouse gas emissions has raised concerns and necessitated further research in climate change mitigation and adaptation. Methane is a prominent greenhouse gas that significantly contributes to climate change, with a substantial amount generated through fermentation processes occurring in the rumen of ruminant animals. The potential of plant secondary metabolites, especially those derived from tannin-rich plants, warrants investigation to modify rumen fermentation and mitigate methane emissions in livestock diets. The objective of this study was to assess the impact of extracts obtained from green and black tea waste on rumen fermentation dynamics and gas (methane) production, utilizing in vitro methods. For this purpose, rumen fluid was collected from two fistulated sheep and subjected to three treatments: (1) a basal diet (control), (2) a basal diet + green tea waste extract (5% of dry matter), (3) a basal diet + black tea waste extract (5% of dry matter). The study assessed the effects of incorporating extracts from green and black tea waste on various parameters, including digestibility, protozoa population, ammonia nitrogen levels, volatile fatty acids, and methane gas production following a 24-h incubation period. Statistical analysis of the data was conducted using SAS software within a completely randomized design framework. The findings indicated that the addition of green and black tea waste extracts significantly decreased methane gas production (p < 0.05), protozoa count (p < 0.05), and ammonia nitrogen concentrations in rumen fluid (p < 0.05) when compared to the control group. The addition of green and black tea waste extracts has significantly altered the concentration of VFAs in rumen fluid (p < 0.05). Specifically, the addition of green tea waste extract has led to a highly significant reduction in acetic acid, (p < 0.01) and the addition of both extracts has resulted in a significant increase in propionic acid (p < 0.05). Consequently, the results suggest that the inclusion of green and black tea waste extracts in livestock diets may effectively mitigate methane emissions in the rumen, thereby reducing feed costs and reducing environmental pollution. Full article

This study assessed the impact of active dry yeast (ADY) on nutrient digestibility and rumen fermentation, using both in vitro and in vivo experiments with lambs. In vitro, ADYs were incubated with rumen fluid and a substrate mixture to assess gas production, pH, volatile fatty acid (VFA) profiles, and lactate concentration. In vivo, Hu lambs were randomly assigned to five dietary treatments: a control group and four groups receiving one of two dosages of either Vistacell or Procreatin7. Growth performance, nutrient digestibility, rumen fermentation parameters, and bacterial community composition were measured. Pro enhanced the propionate molar proportion while it decreased the n-butyrate molar proportion. Vis reduced the lactate concentration in vitro. In the in vivo experiment, Vis increased the propionate molar proportion and the Succinivibrionaceae_UCG-001 abundance while it decreased the n-butyrate molar proportion and the Lachnospiraceae_ND3007 abundance. Additionally, Vis showed a greater impact on improving the NDF digestibility and total VFA concentration in vivo compared to Pro. Overall, the effects of ADYs on rumen fermentation were found to vary depending on the specific ADY used, with Vis being the most suitable for lamb growth. It was observed that Vis promoted propionate fermentation and Succinivibrionaceae_UCG-001 abundance at the expense of reduced n-butyrate fermentation and Lachnospiraceae_ND3007 abundance. Importantly, differences were noted between the outcomes of the in vitro and in vivo experiments concerning the effects of ADYs on rumen fermentation, highlighting the need for caution when generalizing batch culture results to the in vivo effects of ADYs. Full article