Potential protective effects of thiamine supplementation on the ruminal epithelium damage during subacute ruminal acidosis

Effects of yeast β-glucan on fermentation parameters, microbial community structure, and rumen epithelial cell function in high-concentrate-induced yak rumen acidosis in vitro

This study employed a completely randomized design (CRD) to evaluate the effects of graded levels of yeast β-glucan supplementation on subacute ruminal acidosis (SARA) induced by high-concentrate diets in yaks. Seven treatment groups were established: a low-concentrate control (LC; 50 % concentrate + 50 % forage), a high-concentrate control (HC; 80 % concentrate + 20 % forage), and HC diets supplemented with 0.5 %, 1 %, 2 %, 4 %, or 8 % yeast β-glucan. Rumen pH, gas production, and volatile fatty acid (VFA) profiles were measured at 3, 6, 9, 12, and 24 h of in vitro fermentation. At 9, 12, and 24 h, concentrations of deleterious metabolites-lactic acid, endotoxin (LPS), and histamine-were quantified. 16S rRNA gene sequencing was performed to compare microbial community structures among the LC, HC, and HC + 1 % β-glucan (1 % HCG) groups. The effects of fermentation supernatants on inflammatory gene expression and epithelial barrier integrity were evaluated using a yak rumen epithelial cell (YREC) model. Results demonstrated that the LC group maintained ruminal pH > 5.5 at all time points, whereas the HC group exhibited pH < 5.5 after 9, 12, and 24 h. Supplementation with 1-8 % yeast β-glucan significantly elevated pH (P < 0.05) to values comparable with the LC group. Relative to LC, the HC group showed significant reductions in pH, microbial crude protein (MCP), acetate concentration, and acetate:propionate ratio (P < 0.05), concomitant with significant increases in NH₃-N, propionate, butyrate, total VFA, and harmful metabolites (lactic acid, LPS, and histamine) (P < 0.05). Microbial community analysis revealed that HC feeding decreased the relative abundances of specific genera within the Firmicutes and Bacteroidetes phyla. Moreover, the HC diet upregulated pro-inflammatory gene expression and downregulated genes related to oxidative phosphorylation and cytoskeletal integrity in YRECs. Yeast β-glucan supplementation (1-8 %) mitigated SARA-associated perturbations in fermentation parameters-elevating pH, acetate concentration, acetate:propionate ratio, and MCP content; reducing NH₃-N accumulation; and lowering lactic acid, LPS, and histamine concentrations-while modulating key bacterial taxa and attenuating inflammatory responses and epithelial damage. In conclusion, yeast β-glucan effectively alleviates high-concentrate diet-induced ruminal acidosis and promotes rumen health.

Thiamine, gastrointestinal beriberi and acetylcholine signaling

Research has highlighted numerous detrimental consequences of thiamine deficiency on digestive function. These range from impaired gastric and intestinal motility to aberrant changes in pancreatic exocrine function, gastric acidity and disturbances in gut barrier integrity and inflammation. Thiamine and its pharmacological forms, as a primary or adjunctive therapy, have been shown to improve symptoms such as nausea, constipation, dysphagia and intestinal dysmotility, in both humans and animals. This review aims to explore molecular mechanisms underlying the therapeutic action of thiamine in gastrointestinal dysfunction. Our analysis demonstrates that thiamine insufficiency restricted to the gastrointestinal system, i.e., lacking well-known symptoms of dry and wet beriberi, may arise through (i) a disbalance between the nutrient influx and efflux in the gastrointestinal system due to increased demands of thiamine by the organism; (ii) direct exposure of the gastrointestinal system to oral drugs and gut microbiome, targeting thiamine-dependent metabolism in the gastrointestinal system in the first line; (iii) the involvement of thiamine in acetylcholine (ACh) signaling and cholinergic activity in the enteric nervous system and non-neuronal cells of the gut and pancreas, employing both the coenzyme and non-coenzyme actions of thiamine. The coenzyme action relies on the requirement of the thiamine coenzyme form - thiamine diphosphate - for the production of energy and acetylcholine (ACh). The non-coenzyme action involves participation of thiamine and/or derivatives, including thiamine triphosphate, in the regulation of ACh synaptic function, consistent with the early data on thiamine as a co-mediator of ACh in neuromuscular synapses, and in allosteric action on metabolic enzymes. By examining the available evidence with a focus on the gastrointestinal system, we deepen the understanding of thiamine's contribution to overall gastrointestinal health, highlighting important implications of thiamine-dependent mechanisms in functional gastrointestinal disorders.

Transcriptomics insights into glutamine on repairing of histamine-induced Yak rumen epithelial cells barrier damage in vitro

BACKGROUND

Glutamine (Gln) plays a pivotal role in maintaining the integrity of the rumen epithelial barrier in mammals. This study aimed to investigate the effects of Gln on histamine-induced barrier damage in yak rumen epithelial cells (YRECs).

RESULTS

RT-qPCR analysis revealed a significant decrease in the mRNA expression of tight junction proteins (ZO-1, JAM-A, Claudin-1, and Claudin-4) following 24-hour exposure to 20 µM histamine (HIS group) (P < 0.05). In the subsequent experiment, YRECs were first treated with 20 µM histamine for 24 h, followed by 8 mM glutamine for 12 h (HG group). Gln treatment reversed the histamine-induced downregulation of both mRNA and protein levels of tight junction proteins and restored the distribution of ZO-1 at the cell membrane. Transcriptome analysis revealed that co-regulated differentially expressed genes were primarily involved in the mitogen-activated protein kinase (MAPK) signaling pathway and apoptosis. These findings were further corroborated by RT-qPCR, Western blot, and flow cytometry analyses. To determine whether glutamine regulates cell barrier function through the p38 MAPK signaling pathway, 20 µM Skatole, a p38 MAPK agonist, was introduced (SK group). The results showed a significant increase in the p-p38/p38 ratio and a marked decrease in the mRNA and protein expression of tight junction proteins in the SK group compared to the HG group (P < 0.05).

CONCLUSIONS

Glutamine mitigates histamine-induced barrier damage in YRECs through the p38 MAPK signaling pathway and apoptosis regulation.

Effect of Isolation Ruminal Yeast from Ruminants on In Vitro Ruminal Fermentation

In order to obtain high-performing yeast strains from ruminants, it is necessary to select them from species such as beef cattle, dairy cows, goats, and buffalo. A total of 91 isolated yeasts were collected using the standard methods of microbial culture on agar medium followed by streaking on a plate at least three times until pure yeast colonies were formed. The API 20C AUX Kit and sequencing of the D1/D2 domain of the 26S rRNA gene were used to identify the genera Candida spp., namely, C. glabrata (99% identification), C. tropicallis (99%), C. rugosa (98%), and Issatchenkia orientalis (99%). A total of 12 yeast strains (Dc4, 14, 18; Be1, 2, 7; Bu3, 4, 7; and Go10, 16, 19) were chosen for further analyses. The performance criteria included the ability to tolerate pH values between 3.5 and 7.5, total volatile fatty acids (TVFAs, 0, 0.25, 0.5, 1, 2, and 4% of broth medium), anaerobic growth rate, and in vitro gas production efficiency. First, when all strains were grown at pH values between 3.5 and 7.5, Bu3 and Dc18 performed better than the other strains. Second, at a ruminal pH of 6.5 and a TVFA concentration of between 2 and 4% of the broth medium, strain Bu3 was more resistant than the other strains. Under anaerobic conditions, all strains experienced a decline in viable cell counts when compared with those under aerobic conditions. However, compared to strains Dc14, Be1, Be2, Be7, and Bu3, strain Dc18 exhibited more viable cells under anaerobic conditions in broth medium. The response of strain Dc18 did not differ from those of strains Dc4, Bu4, Bu7, or G16. Strains Be7, Bu3, and Dc18 were used for an in vitro fermentation experiment involving incubation for 2, 4, 6, 8, 10, 12, 24, 36, 48, and 72 h. Three ruminal cannulated dairy cows were used as donors of ruminal fluid. The treatments were run in triplicate. The addition of yeast culture had no effect on gas kinetics, gas accumulation, or the ratio of acetic acid and propionic acid, but led to significantly greater butyric acid concentrations at 24 h of incubation. In conclusion, strain Dc18 isolated from dairy cows is suitable for future studies of probiotic yeast development.

Effects of High-Concentrate Diets on Growth Performance, Serum Biochemical Indexes, and Rumen Microbiota in House-Fed Yaks

The aim of this study is to determine the effects of a high-concentrate diet on growth performance, serum biochemical indexes, and rumen microbiota in house-fed yaks. Sixteen male yaks (body weight, 151.73 ± 14.11 kg; 18 months) were randomly allocated into two dietary treatments: a group with a low level of concentrate (n = 8, LC, concentrate-forage = 40:60) and a group with a high level of concentrate (n = 8, HC, concentrate-forage = 60:40). We found that compared with the LC group, the average daily feed intake (ADFI), the average daily gain (ADG), and the serum albumin (ALB) concentration in the HC group were significantly increased (p < 0.05). The rumen bacterial compositions also differed significantly between the groups, as indicated by principal coordinate analysis (p < 0.05). Firmicutes and Bacteroidota were the main dominant phyla of rumen bacteria in yaks. Compared with the LC group, the relative abundance of Firmicutes in the HC group was significantly increased (p < 0.05) and the relative abundance of Bacteroidota was significantly decreased (p < 0.05). At the genus level, Rikenellaceae_RC9_gut_group, Succiniclasticum, Prevotella, Christensenellaceae_R-7_group, and NK4A214_group had the highest relative abundance. The relative abundance of Christensenellaceae_R-7_group in the HC group was significantly higher than that in the LC group (p < 0.05). The PICRUSt 2 results showed a significant enrichment in glycosaminoglycan degradation, apoptosis, and ECM-receptor interaction in HC relative to LC (p < 0.05). In conclusion, high-concentrate diets can enhance growth performance and alter the compositions and functions of ruminal bacterial communities in yaks.

Metabolomics and proteomics insights into subacute ruminal acidosis etiology and inhibition of proliferation of yak rumen epithelial cells in vitro

BACKGROUND

Untargeted metabolomics and proteomics were employed to investigate the intracellular response of yak rumen epithelial cells (YRECs) to conditions mimicking subacute rumen acidosis (SARA) etiology, including exposure to short-chain fatty acids (SCFA), low pH5.5 (Acid), and lipopolysaccharide (LPS) exposure for 24 h.

RESULTS

These treatments significantly altered the cellular morphology of YRECs. Metabolomic analysis identified significant perturbations with SCFA, Acid and LPS treatment affecting 259, 245 and 196 metabolites (VIP > 1, P < 0.05, and fold change (FC) ≥ 1.5 or FC ≤ 0.667). Proteomic analysis revealed that treatment with SCFA, Acid, and LPS resulted in differential expression of 1251, 1396, and 242 proteins, respectively (FC ≥ 1.2 or ≤ 0.83, P < 0.05, FDR < 1%). Treatment with SCFA induced elevated levels of metabolites involved in purine metabolism, glutathione metabolism, and arginine biosynthesis, and dysregulated proteins associated with actin cytoskeleton organization and ribosome pathways. Furthermore, SCFA reduced the number, morphology, and functionality of mitochondria, leading to oxidative damage and inhibition of cell survival. Gene expression analysis revealed a decrease the genes expression of the cytoskeleton and cell cycle, while the genes expression associated with inflammation and autophagy increased (P < 0.05). Acid exposure altered metabolites related to purine metabolism, and affected proteins associated with complement and coagulation cascades and RNA degradation. Acid also leads to mitochondrial dysfunction, alterations in mitochondrial integrity, and reduced ATP generation. It also causes actin filaments to change from filamentous to punctate, affecting cellular cytoskeletal function, and increases inflammation-related molecules, indicating the promotion of inflammatory responses and cellular damage (P < 0.05). LPS treatment induced differential expression of proteins involved in the TNF signaling pathway and cytokine-cytokine receptor interaction, accompanied by alterations in metabolites associated with arachidonic acid metabolism and MAPK signaling (P < 0.05). The inflammatory response and activation of signaling pathways induced by LPS treatment were also confirmed through protein interaction network analysis. The integrated analysis reveals co-enrichment of proteins and metabolites in cellular signaling and metabolic pathways.

CONCLUSIONS

In summary, this study contributes to a comprehensive understanding of the detrimental effects of SARA-associated factors on YRECs, elucidating their molecular mechanisms and providing potential therapeutic targets for mitigating SARA.

Effects of yeast culture on in vitro ruminal fermentation and microbial community of high concentrate diet in sheep

This research aimed to investigate effects of different yeast culture (YC) levels on in vitro fermentation characteristics and bacterial and fungal community under high concentrate diet. A total of 5 groups were included in the experiment: control group without YC (CON), YC1 (0.5% YC proportion of substrate dry matter), YC2 (1%), YC3 (1.5%) and YC4 (2%). After 48 h of fermentation, the incubation fluids and residues were collected to analyze the ruminal fermentation parameters and bacterial and fungal community. Results showed that the ruminal fluid pH of YC2 and YC4 groups was higher (P < 0.05) than that of CON group. Compared with CON group, the microbial protein, propionate and butyrate concentrations and cumulative gas production at 48 h of YC2 group were significantly increased (P < 0.05), whereas an opposite trend of ammonia nitrogen and lactate was observed between two groups. Microbial analysis showed that the Chao1 and Shannon indexes of YC2 group were higher (P < 0.05) than those of CON group. Additionally, YC supplementation significantly decreased (P < 0.05) Succinivibrionaceae_UCG-001, Streptococcus bovis and Neosetophoma relative abundances. An opposite tendency of Aspergillus abundance was found between CON and YC treatments. Compared with CON group, the relative abundances of Prevotella, Succiniclasticum, Butyrivibrio and Megasphaera elsdenii were significantly increased (P < 0.05) in YC2 group, while Apiotrichum and unclassified Clostridiales relative abundances were decreased (P < 0.05). In conclusion, high concentrate substrate supplemented with appropriate YC (1%) can improve ruminal fermentation and regulate bacterial and fungal composition.

Glycyrrhizin inhibits LPS-induced inflammatory responses in goat ruminal epithelial cells in vitro

Inflammation plays a crucial role in the progression of Subacute Ruminal Acidosis (SARA). The experiment was designed to investigate anti-inflammatory effects of glycyrrhizin on goats ruminal epithelial cells (GREC) which were induced SARA by Lipopolysaccharide (LPS) in vitro. The GREC were induced SARA by adding LPS at the concentration of 5 μm and glycyrrhizin was added at different concentration of 0, 60, 90, 120, 150 μm. The structural integrity of LPS-induced GREC with the treatment of glycyrrhizin were observed by electron microscope; The levels of inflammatory factors TNF-α, IL-1β, IL-6, IL-8 and IL-12 were measured by ELISA; The number of Zo-1 and Occludin were measured, the expression of tight junction protein Occludin were measured by Western blot, and the mRNA expression of NF-κB, TNF-α, IL-1β, IL-6, IL-8 and IL-12 were measured in vitro. The results showed that higher concentration treatment of glycyrrhizin led to better morphology in LPS-induced GREC. Glycyrrhizin inhibited the growth of inflammatory factors TNF-α, IL-1β, IL-6, IL-8 and IL-12 in a dose-dependent manner. The number of ZO-1 and Occludin increased with the increase of adding of glycyrrhizin. Western blot analysis showed that the expression of tight junction protein Occludin in LPS-induced GREC increased with the adding of glycyrrhizin in a dose-dependent manner. Furthermore, the mRNA expression of NF-κB, TNF-α, IL-1β, IL-6, IL-8 and IL-12 decreased significantly with the increase treatment of glycyrrhizin. Glycyrrhizin significantly inhibits LPS-induced inflammatory mediators in GREC and the effects are better with the increase treatment of glycyrrhizin in vitro.

Sodium Propionate Relieves LPS-Induced Inflammation by Suppressing the NF-ĸB and MAPK Signaling Pathways in Rumen Epithelial Cells of Holstein Cows

Subacute ruminal acidosis (SARA) is a prevalent disease in intensive dairy farming, and the rumen environment of diseased cows acidifies, leading to the rupture of gram-negative bacteria to release lipopolysaccharide (LPS). LPS can cause rumentitis and other complications, such as liver abscess, mastitis and laminitis. Propionate, commonly used in the dairy industry as a feed additive, has anti-inflammatory effects, but its mechanism is unclear. This study aims to investigate whether sodium propionate (SP) reduces LPS-induced inflammation in rumen epithelial cells (RECs) and the underlying mechanism. RECs were stimulated with different time (0, 1, 3, 6, 9, 18 h) and different concentrations of LPS (0, 1, 5, 10 μg/mL) to establish an inflammation model. Then, RECs were treated with SP (15, 25, 35 mM) or 10 μM PDTC in advance and stimulated by LPS for the assessment. The results showed that LPS (6h and 10 μg/mL) could stimulate the phosphorylation of NF-κB p65, IκB, JNK, ERK and p38 MAPK through TLR4, and increase the release of TNF-α, IL-1β and IL-6. SP (35 mM) can reduce the expression of cytokines by effectively inhibiting the NF-κB and MAPK inflammatory pathways. This study confirmed that SP inhibited LPS-induced inflammatory responses through NF-κB and MAPK in RECs, providing potential therapeutic targets and drugs for the prevention and treatment of SARA.

The effects of antibiotic-free supplementation on the ruminal pH variability and methane emissions of beef cattle under the challenge of subacute ruminal acidosis (SARA)

Subacute ruminal acidosis (SARA) in feedlot cattle during the feed transition to grain-based diets is a significant constraint to animal health and productivity. This experiment assessed an antibiotic-free supplement (ProTect®) effects on ruminal pH variability and methane (CH₄) emissions of cattle during the challenge of SARA. Ten 18-month-old Angus steers (472 ± 4.8 kg) were randomly allocated into monensin (n = 5) and ProTect® groups (n = 5) and progressively introduced to grain diets incorporating monensin or ProTect® for 36 days of the experiment [starter (7 days; 45% grain), T1 (7 days; 56% grain), T2 (7 days; 67% grain), finisher (15 days; 78% grain)]. The pH variability on the finisher period was reduced by the ProTect® supplement (6.6% vs. 5.2%; P < 0.01), with CH₄ emissions being significantly higher relative to the monensin group [88.2 g/day (9.3 g CH₄/kg DMI) vs. 133.7 g/day (14.1 g CH₄/kg DMI); P < 0.01]. There was no difference between treatments in the time spent on the ruminal pH < 5.6 or < 5.8 (P > 0.05). The model evaluation for the ruminal pH variation indicated that the mean absolute error (MAE) proportion for both groups was good within the same range [4.05% (monensin) vs. 4.25% (ProTect®)] with identical root mean square prediction error (RMSPE) (0.34). It is concluded that the ProTect® supplement is an effective alternative to monensin for preventing SARA in feedlot cattle by managing ruminal pH variation during the transition to high-grain diets. Both monensin and ProTect® supplemented cattle exhibited lower CH₄ yield compared to cattle fed forages and low-concentrate diets.

The effects of a nutritional packet (live yeast, vitamins C and B1, and electrolytes) offered to steers in a calf-fed system on growth performance, nutrient digestion, feeding behavior, carcass characteristics, and ruminal variables

Effects of a nutritional packet strategically offered to calf-fed system steers on growth performance, nutrient digestibility, feeding behavior, ruminal variables, and carcass characteristics were evaluated. Angus crossbred steer-calves (N = 60; body weight [BW] = 234 ± 4 kg) were used in a randomized complete block design (block = BW) and stratified into two treatments: 1) control; and 2) 30 g/steer-daily (dry matter [DM] basis) of a nutritional packet containing (steer-daily basis): Live yeast (Saccharomyces cerevisiae; 1.7 × 10¹⁰ CFU), vitamin C (Ascorbic acid, 162 mg), vitamin B1 (thiamin hydrochloride, 400 mg), sodium chloride (2.4 g), and potassium chloride (2.4 g). Animals were offered (electronic feed-bunks [SmartFeed, C-Lock Inc., Rapid City, SD]), a steam-flaked corn-based finishing diet to ad libitum (individual intake), once daily for 233 d. Treatments were offered during the first and last 60 days on feed (DOF). The GLIMMIX procedure of SAS was used, with steer as the experimental unit, treatment and phase (for feeding behavior and digestibility) as fixed effects, and BW-block as a random effect. Steers offered the nutritional packet had 14% less (P < 0.01) intake and 18% greater (P = 0.01) feed efficiency during the initial 30 DOF. Intake (days 0 to 233) was 6% greater (P = 0.02) for steers offered the nutritional packet, while BW gain was not different (P ≥ 0.44). Greater (P = 0.02) dressing percent (61.1% vs. 62%) for steers offered the packet was observed, while other carcass variables were not different (P ≥ 0.33). Digestibility of DM, organic matter, and fiber were greater (P < 0.01) for steers offered the packet. Steers offered the packet spent 13% less time eating during the first 60 DOF, while during the last 60 DOF a 14% greater meal frequency and 12.3% smaller mean meal size (treatment × phase interaction, P < 0.02) were observed. Steers offered the packet had a reduced (P ≤ 0.01) mean meal duration during both phases. Regardless of treatment, a decreased rumination (P ≤ 0.03) and chewing (P ≤ 0.01) activities were observed for the last 60 DOF compared to the first 60 DOF. Ruminal papillae area was 30% greater (P = 0.02) and the total volatile fatty acid (VFA) tended (P = 0.09) to be greater for steers offered the nutritional packet. The nutritional packet offered to calf-fed steers improved feed efficiency during the initial 30 d after arrival, while inducing superior overall intake, nutrient digestibility, dressing percentage, ruminal papillae area, and total ruminal VFA.

Effects of the higher concentrate ratio on the production performance, ruminal fermentation, and morphological structure in male cattle-yaks

Background

The present study evaluated the effects of the different concentrate‐to‐forage ratio on the parameters of production, ruminal fermentation, blood biochemical indices, and ruminal epithelial morphological structure of the male cattle‐yaks.

Methods

Eight male cattle‐yaks (280 ± 10 kg of body weight) were randomly divided into the high concentrate (HighC, 70% concentrate feeds on a dry matter basis) and low concentrate (LowC, 50% concentrate feeds on a dry matter basis) groups. All the animals were regularly provided rations twice a day at 08:00 and 16:00 h and had free access to water. The experiment lasted for 37 days.

Results

The dry matter intake and average daily gain of the HighC group were higher (p < 0.05) than those of LowC group. Moreover, a high concentrate diet was found to significantly increase (p < 0.05) the total volatile fatty acid (TVFA) production, and the ratio of propionate and butyrate in TVFA. On the contrary, the ruminal pH, the ratio of isobutyrate and isovalerate, and the acetate‐to‐propionate were significantly decreased (p < 0.05) after high concentrate feeding. The lipopolysaccharide concentrations of the ruminal fluid and plasma in the HighC group were higher (p < 0.05) than those of the LowC group. The results of the ruminal histomorphology showed the rumen to possess an inflammatory reaction.

Conclusion

These findings revealed that upon higher dry matter intake and average daily gain, high concentrate feeding altered the rumen fermentation and morphology, inducing the ruminal inflammation of the cattle‐yak.