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This study aimed to research the effects of different dietary concentrate to forage (C:F) ratio on growth performance, rumen fermentation and bacteria diversity of barn feeding Tibetan sheep. The experiment contains fiver treatments (HS1, HS2 HS3, HS4 and HS5; n  = 8, respectively) based on dietary C:F ratios 0:100, 15:85, 30:70, 45:55, and 60:40, respectively. The ruminal bacterial community structure was investigated through high-throughput sequencing of 16S rRNA genes in V4 hypervariable region. The results showed that increasing dietary concentrate feed level from 0% to 60% exerted a positive effect on DMI, BW gain, gain rate and feed conversation ratio (F CR ) in Tibetan sheep. The increases dietary concentrate feed level elevatedNH 3 -N, propionate and valerate concentrations, whereas, reduced molar ratio of acetate to propionate (A/P ratio) ( P  < 0.05). For rumen bacterial diversity, increases in dietary concentrate content contributed to lower alpha diversity indexes including Shannon wiener, Chao1 and observed species, meanwhile, significantly increased the abundances of the phylum Bacteroidetes and the genus Prevotella_1 ( P  < 0.05). In conclusion, increases dietary concentrate content improved the growth performance and Tibetan sheep fed diets of 45% concentrate obtained a better performance; the inclusion of concentrate in feed changed rumen fermentation from acetate fermentation to propionate fermentation, and improved the energy utilization efficiency of Tibetan sheep; the increased in concentrate content significantly reduced rumen bacteria diversity and changed the abundance of some core bacteria.

Objective: The present study aimed to determine the influence of different rumen degradable protein (RDP)/non-fibrous carbohydrate (NFC) proportions on ruminal fermentation characteristics, gas production kinetics, and microbial populations. Materials and Methods: An in vitro batch culture trial was conducted using different combinations of RDP/NFC proportions categorized into six dietary treatments (n = 5 per treatment, three replicative runs). Combinations of balanced RDP/NFC proportions were 60% RDP: 35% NFC (P1, 1:3.65), 60% RDP: 40% NFC (P2, 1:4.17), 65% RDP: 35% NFC (P3, 1:3.37), 65% RDP: 40% NFC (P4, 1:3.85), 55% RDP: 39% NFC (P5, 1:5.06), and 55% RDP: 41% NFC (P6, 1:5.32). Results: The present study observed that the combination of a high proportion of RDP and NFC influenced in vitro rumen fermentation, such as volatile fatty acid and NH₃ concentrations, and in vitro organic matter digestibility. However, a high RDP (65%) with a low NFC (35%) positively influenced total gas production, gas kinetics, enteric methane production, and microbial population in the rumen. Conclusion: In this study, we revealed that the ratios of RDP and NFC in animal feed have a considerable impact on rumen fermentation, microbial population, and digestibility.

Previous studies have shown that Bacillus subtilis natto affects rumen fermentation and rumen microbial community structure, which are limited to detect a few microbial abundances using traditional methods. However, the regulation of B. subtilis natto on rumen microorganisms and the mechanisms of microbiota that affect rumen fermentation is still unclear. This study explored the effects of live and autoclaved B. subtilis natto on ruminal microbial composition and diversity in vitro using 16S rRNA gene sequencing and the underlying mechanisms. Rumen fluid was collected, allocated to thirty-six bottles, and divided into three treatments: CTR, blank control group without B. subtilis natto; LBS, CTR with 109 cfu of live B. subtilis natto; and ABS, CTR with 109 cfu of autoclaved B. subtilis natto. The rumen fluid was collected after 0, 6, 12, and 24 h of fermentation, and pH, ammonia nitrogen (NH3-N), microbial protein (MCP), and volatile fatty acids (VFAs) were determined. The diversity and composition of rumen microbiota were assessed by 16S rRNA gene sequencing. The results revealed LBS affected the concentrations of NH3-N, MCP, and VFAs (p < 0.05), especially after 12 h, which might be attributed to changes in 18 genera. Whereas ABS only enhanced pH and NH3-N concentration compared with the CTR group (p < 0.05), which might be associated with changes in six genera. Supplementation with live B. subtilis natto improved ruminal NH3-N and propionate concentrations, indicating that live bacteria were better than autoclaved ones. This study advances our understanding of B. subtilis natto in promoting ruminal fermentation, providing a new perspective for the precise utilization of B. subtilis natto in dairy rations.

Rumen cud transfaunation re-establishes rumen micro environment and improves fermentation in recipient animals affected with digestive disorders. Preserving rumen cud or fluid will increase its availability for the treatment of rumen fermentation disorders, without having to maintain donor animals. Rumen fluid collected from healthy goats, fed standard ration having roughage 70% and concentrate 30%, was lyophilized (prefreezing -80 °C, 48 h; lyophilization -45 °C, 32 h) using 5% glycerol as cryoprotectant. The 16 S metagenome analysis of the lyophilized rumen fluid (LRF) revealed an abundance of Prevotella (33.2%). Selenomonas ruminantium (1.87%) and Megasphaera elsdenii (0.23%) were also present. Twenty-four goats having history of high grain feeding and exhibiting clinical symptoms of rumen fermentation disorders were randomly distributed into either one of the two treatment groups viz., T1 = oral administration of LRF 31 g/animal/day and T2 = oral administration of sodium bicarbonate (SB) 15 g/animal/day. Post intervention LRF and SB, improved animal body condition, feed intake, fecal consistency, elevated the ruminal pH at 48 h, reduced propionate and lactate at 48 h, reduced total volatile fatty acids (TVFA) and ammonia nitrogen at 24 h. Significant reduction in serum blood urea nitrogen (BUN) and urea levels were observed even from 24 h post intervention irrespective of the treatments. LRF significantly improved acetate and decreased propionate production compared to SB. LRF at 7.5% (v/v) can thus be used to counteract ruminal fermentation disorders in goats sequel to high grain ration.

Microplastics (MPs) have emerged as a significant environmental threat, infiltrating livestock systems. This study presents the first in vitro investigation of the effects of low-density polyethylene (LDPE) MP contamination on rumen fermentation dynamics and feed utilization in a simulated ruminal digestive system. Concentrate feed was incubated in buffered rumen fluid collected from lambs, supplemented with LDPE MPs at concentrations of 3.3 g/L and 6.6 g/L and compared to the concentrate incubated in the buffered rumen fluid without MP contamination. The results demonstrate that both levels of LDPE MPs significantly altered rumen fermentation dynamics by reducing asymptotic gas production by 11% and 15% and increasing the constant rate of gas production by 16% and 19% at low and high addition levels, respectively, compared to the control. However, the early-stage fermentation dynamics remained unaffected. Furthermore, both levels of LDPE MPs reduced rumen protozoal populations (20% and 23%) and ammonia-nitrogen levels by 11% at both of addition levels. Despite these disruptions, rumen pH remained unaffected. Increasing the addition level of LDPE from 3.3 to 6.6 g/L did not exacerbate the disruptions. The results of this study highlight the potential risks posed by LDPE MPs in ruminal nutrition. Further in vivo investigations are essential to validate these findings and assess their impact on animal performance.

Background Garlic ( Allium sativum ) contains different bioactive compounds that have antimicrobial activities, which might modify rumen fermentation and improve animal performance. This study investigated the effect of garlic powder supplementation on growth performance, rumen fermentation and microbiota, blood metabolites, and immunity in Barki lambs. Twelve Barki lambs were assigned into two dietary treatments ( n  = 6): basal diet (control group) or basal diet supplemented with garlic powder as 2% of dry matter (DM) intake. The basal diet consisted of alfalfa hay and a concentrate feed mixture. Results The results showed that garlic supplementation enhanced the growth performance, blood immunoglobulins IgG and IgA, rumen pH, and the proportions of propionic, isobutyric, and isovaleric ( P  < 0.05). Moreover, the rumen ammonia, predicted methane, and microbial alpha diversity were declined due to garlic supplementation ( P  < 0.05). Principal Co-ordinate analysis (PCoA) revealed that microbial communities were clustered according to dietary treatments. The bacterial community was dominated by phyla Bacteroidota and Firmicutes. The supplementation improved the relative abundance of the family Ruminococcaceae, genus Prevotella and Butyrivibrio which were correlated positively with growth performance and blood immunity ( P  < 0.05). Conclusions The results explain that garlic powder could modify rumen microbiota to improve rumen fermentation, immunity, and growth performance in growing lambs.

This study aimed to investigate the effects of different storage times of the mixed inoculum on in vitro rumen fermentation characteristics, microbial diversity, and community composition. The experiment was divided into five groups, with mixed inoculum composed of fresh rumen fluid and culture medium being stored at 39 °C for 0 h (H0), 12 h (H12), 24 h (H24), 36 h (H36), and 48 h (H48). After 48 h of in vitro fermentation, the fermentation fluid was collected to assess rumen fermentation characteristics and microbial community composition. The H24 group showed higher total gas production, ammoniacal nitrogen levels, and total volatile fatty acids, as well as higher concentrations of individual volatile fatty acids except propionate, compared to the H0 and H48 groups (p < 0.05). The Shannon and Simpson evenness indices were significantly higher in the H0, H12, and H24 groups than in the H48 group (p < 0.05). A total of nine phyla and sixteen genera involved in starch and fiber degradation were found to be more abundant in the H24 or H48 groups (p < 0.05). Moreover, nine predicted metabolic pathways were observed to be significantly enriched in either the H24 or H48 group (p < 0.05). Both principal coordinates analysis (PCoA) and non-metric multidimensional scaling (NMDS) analysis revealed distinct clustering patterns among the H0, H12, H24, H36, and H48 groups, and analysis of similarities (ANOSIM) confirmed these significant differences (R = 1.00, p < 0.05). This study demonstrates that the storage time of mixed inoculum influences rumen fermentation characteristics and microbial community composition in a time-dependent manner. It is recommended to use a mixed inoculum that has been stored within 24 h in an anaerobic environment at 39 °C for in vitro rumen fermentation tests. This study offers valuable microbial insights into the storage strategies for mixed inoculum, thereby improving the methodologies for variable control in in vitro rumen fermentation techniques.

This study aimed to explore the effects of different incubation temperatures on ruminal fermentation and rumen microorganisms and determine the appropriate protein and energy levels to enhance microbial protein synthesis using an in vitro system. Rumen inoculum was collected from two fistulated Holstein heifers (trial 1: BW: 652.3 kg ± 25.2; trial 2: BW: 683.3 kg ± 30.2) and assessed using a closed-batch culture system. The experimental model employed a 2 × 5 factorial arrangement using incubation temperatures set to 39 and 41 °C, with protein levels set to 12.0, 13.5, 15.0, 16.5, and 18.0% of DM in trial 1 or with energy levels set to 2.4, 2.5, 2.6, 2.7, and 2.8 Mcal/kg of DM in trial 2. The data were analyzed using the MIXED procedure. The results showed increased (p < 0.05) NH3-N concentrations and total volatile fatty acids (TVFAs) with higher incubation temperatures, while the liquid-associated bacterial (LAB) amounts decreased (p < 0.05) in trials 1 and 2. The interaction between the energy level and incubation temperature affected (p < 0.05) the LAB protein levels in trial 2. Higher protein levels led to increased (p < 0.05) NH3-N and acetate concentrations, but it decreased (p < 0.05) the propionate percentage. Conversely, higher energy levels decreased (p < 0.05) the amount of acetate and increased the propionate concentration, altering the acetate-to-propionate ratio. However, no interaction involving TVFA and LAB was observed between the incubation temperature and the protein or energy levels. Changes in the NH3-N, TVFAs, and LAB protein amounts were observed under different incubation temperatures and energy levels. In conclusion, these findings provide insight into the metabolic adaptation under different ruminal temperatures and the impacts of dietary adjustments on rumen fermentation and microbial activity. However, there are limitations to replicating the complex physiological responses that occur within the whole body solely through in vitro experiments.

The considerable contribution of ruminant livestock to methane emissions has become a major global concern in recent years. Although dietary approaches for reducing ruminant methane emissions have been explored, the sustainable potential of probiotics to influence rumen function and lower methane production has increasingly attracted research attention. While previous studies have focused on single or dual-strain probiotics, this study is among the first to evaluate the synergistic effects of quadric-strain formulations. Hence, this study aimed to evaluate the impact of multi-strain probiotic blends, each at two distinct concentrations on rumen fermentation, nutrient degradability, and methane emission in sheep using an in vitro gas production technique following a completely randomized design. The basal diet with no probiotic supplements served as a control, while the supplemented bacterial combinations were Bacillus licheniformis, Lactobacillus acidophilus, L. bulgaricus, and Bifidobacterium bifidum (ABLB; at a ratio of 1:1:1:1) at levels of 2 × 10 9 (ABLB2) and 4 × 10 9 (ABLB4) CFU/g of feed, and Lactobacillus casei, Lactobacillus plantarum, Bacillus subtilis plus Bifidobacterium bifidum (CPSB; at a ratio of 1:1:1:1) at levels of 2 × 10 9 (CPSB2) and 4 × 10 9 (CPSB4) CFU/g of feed. Probiotic supplementation significantly improved in vitro dry matter and fiber degradability (IVDMD and IVCFD), with the most effective results observed in ABLB treatments. These blends also reduced methane production and ammonia-N concentrations, while increasing total volatile fatty acids (TVFA), indicating more efficient fermentation. Protozoa counts were notably lower in treated groups, supporting the role of probiotics in mitigating methane via microbial modulation ( P  < 0.01). Probiotic supplementation did not affect the values of pH ( P  > 0.05). Predictive values for metabolizable energy (ME), net energy for lactation (NEL), and organic matter digestibility (OMD) were improved across treatments. These findings highlight the potential of targeted probiotic formulations to enhance rumen efficiency and reduce environmental emissions in ruminant systems.

The main objective of this study was to develop practical models to assess and predict the adequacy of dietary fiber in high-yielding dairy cows. We used quantitative methods to analyze relevant research data and critically evaluate and determine the responses of ruminal pH and production performance to different variables including physical, chemical, and starch-degrading characteristics of the diet. Further, extensive data were used to model the magnitude of ruminal pH fluctuations and determine the threshold for the development of subacute ruminal acidosis (SARA). Results of this study showed that to minimize the risk of SARA, the following events should be avoided: 1) a daily mean ruminal pH lower than 6.16, and 2) a time period in which ruminal pH is <5.8 for more than 5.24h/d. As the content of physically effective neutral detergent fiber (peNDF) or the ratio between peNDF and rumen-degradable starch from grains in the diet increased up to 31.2±1.6% [dry matter (DM) basis] or 1.45±0.22, respectively, so did the daily mean ruminal pH, for which a asymptotic plateau was reached at a pH of 6.20 to 6.27. This study also showed that digestibility of fiber in the total tract depends on ruminal pH and outflow rate of digesta from reticulorumen; thereby both variables explained 62% of the variation of fiber digestibility. Feeding diets with peNDF content up to 31.9±1.97% (DM basis) slightly decreased DM intake and actual milk yield; however, 3.5% fat-corrected milk and milk fat yield were increased, resulting in greater milk energy efficiency. In conclusion, a level of about 30 to 33% peNDF in the diet may be considered generally optimal for minimizing the risk of SARA without impairing important production responses in high-yielding dairy cows. In terms of improvement of the accuracy to assessing dietary fiber adequacy, it is suggested that the content of peNDF required to stabilize ruminal pH and maintain milk fat content without compromising milk energy efficiency can be arranged based on grain or starch sources included in the diet, on feed intake level, and on days in milk of the cows.