Effect of sodium concentration and mucosal pH on apical uptake of acetate and butyrate, and barrier function of the isolated bovine ruminal epithelium

Saccharomyces cerevisiae and Kluyveromyces marxianus yeast co-cultures modulate the ruminal microbiome and metabolite availability to enhance rumen barrier function and growth performance in weaned lambs

In lambs, weaning imposes stress that can contribute to impaired rumen epithelial barrier functionality and immunological dysregulation. In this study, the effects of a yeast co-culture consisting of Saccharomyces cerevisiae and Kluyveromyces marxianus (NM) on rumen health in lambs was evaluated, with a focus on parameters including growth performance, ruminal fermentation, and epithelial barrier integrity, ruminal metabolic function, and the composition of the ruminal bacteria. In total, 24 lambs were grouped into four groups of six lambs including a control (C) group fed a basal diet, and N, M, and NM groups in which lambs were fed the basal diet respectively supplemented with S. cerevisiae yeast cultures (30 g/d per head), K. marxianus yeast cultures (30 g/d per head), and co-cultures of both yeasts (30 g/d per head), the experiment lasted for 42 d. Subsequent analyses revealed that relative to the C group, the average daily gain (ADG) of lambs in the NM group was significantly greater and exhibited significant increases in a range of mRNA relative expression including monocarboxylate transporter 1 (MCT1), (Na+)/hydrogen (H+) exchanger 1 (NHE1), (Na+)/hydrogen (H+) exchanger 3 (NHE3), proton-coupled amino acid transporter 1 (PAT1), vacuolar H+-ATPase (vH+ ATPase), claudin-1, occludin in the rumen epithelium (P < 0.05). Compared with the C group, the pH of the rumen contents in the NM group was significantly decreased , and the concentrations of acetate, propionate, and butyrate were significantly increased (P < 0.05). Analysis of the rumen bacteria showed that the NM group exhibited increases in the relative abundance of Prevotella, Treponema, Moryella, Fibrobacter, CF231 and Ruminococcus (P < 0.05). Metabolomics analyses revealed an increase in the relative content of phthalic acid and cinnamaldehyde in the NM group as compared to the C group (P < 0.05), together with the greater relative content of L-tyrosine, L-dopa, rosmarinic acid, and tyrosol generated by the tyrosine metabolic pathway (P < 0.05). Spearman's correlation analyses revealed relative abundance levels of Fibrobacter and Ruminococcus were positively correlated with the mRNA relative expression levels of PAT1, NHE3, and zonula occluden-1 (ZO-1), as well as with tyrosol, phthalic acid, and cinnamaldehyde levels (P < 0.05). Ultimately, these results suggest that dietary supplementation with NM has a wide range of beneficial effects on weaned lambs and is superior to single bacterial fermentation. These effects include improvements in daily gain and rumen epithelial barrier integrity, as well as improvements in the composition of the rumen microbiome, and alterations in tyrosine metabolic pathways.

The effects of dietary cation-anion difference and dietary buffer for lactating dairy cattle under mild heat stress with night cooling

The objective of this study was to investigate the interactive effect of dietary cation-anion difference (DCAD) and dietary buffer supply on DMI, ruminal fermentation, milk and milk component yields, and gastrointestinal tract (GIT) permeability in lactating dairy cattle exposed to mild heat stress. Sixteen lactating Holstein cows, including 8 ruminally cannulated primiparous (80 ± 19.2 DIM) and 8 non-cannulated multiparous (136 ± 38.8 DIM) cows, were housed in a tie-stall barn programmed to maintain a temperature-humidity index (THI) between 68 and 72 from 0600 h to 1600 h followed by natural night cooling. The experimental design was a replicated 4 × 4 Latin rectangle (21-d periods) with a 2 × 2 factorial treatment arrangement. Diets contained a low DCAD (LD; 17.5 mEq/100g of DM) or high DCAD (HD; 39.6 mEq/100g of DM) adjusted using NH4Cl and Na-acetate, with low (LB; 0% CaMg(CO3)2) or high buffer (HB; 1% CaMg(CO3)2). In addition to measurement of feed intake, ruminal fermentation, and milk and milk component yields, a ruminal dose of Cr-EDTA and an equimolar abomasal dose of Co-EDTA were used to evaluate total and post-ruminal gastrointestinal tract permeability, respectively. Treatments had no effect on DMI, ruminal short-chain fatty acid concentrations, or ruminal pH. Feeding HD improved blood acid-base balance, increased urine volume by 4 ± 1.5 kg/d, and increased milk fat by 0.14 ± 0.044 percentage units and milk fat yield by 36.5 ± 16.71 g/d. HB reduced milk fat percentage by 0.11 ± 0.044 percentage units and had no effect on milk fat yield. The HB treatments reduced urinary excretion of Co by 27% and tended to reduce urinary Cr excretion by 10%. Across all treatments, 72% of the Cr recovery was represented by Co suggesting that much of the permeability responses were post-ruminal during mild heat stress. In conclusion, increasing DCAD through greater Na supply during mild heat stress improved blood acid-base balance and may increase milk fat yield. Dietary inclusion of CaMg(CO3)2 improved post-ruminal GIT barrier function despite a lack of low ruminal pH. As there appeared to be a limited interactive effect between DCAD and buffer, increased DCAD and provision of buffer seem to independently influence physiological and performance responses in lactating dairy cows exposed to mild heat with night cooling.

Effect of butyrate sources in a high-concentrate diet on rumen structure and function in growing rams

Dietary butyrate is considered to have mostly positive impacts on the ruminal epithelium. However, its supplementation in a high-concentrate diet may not be justified as excessive ruminal butyrate may negatively affect the rumen. Furthermore, butyrate impact on the rumen may depend on its source. Thirty-two Świniarka growing rams (30.6 ± 2.5 kg; 11-14 months of age) were used to investigate the effect of a high-concentrate diet and sodium butyrate (SB) or tributyrin (TB) supplementation in a high-concentrate diet on the rumen structure and selected functions. The rams were allocated to four treatments and fed diets with: (1) low concentrate inclusion (22.5% of diet DM; L); (2) high concentrate inclusion (60% of diet DM; H); (3) H with SB (3.2% of diet DM; H+SB); and (4) H with TB (2.93% of diet DM; H+TB). The preplanned contrasts were used for treatment comparisons (L vs H treatments (H, H+SB, and H+TB), H vs H+SB, and H vs H+TB). The BW, BW gain and DM intake did not differ between treatments. In the atrium ruminis, epithelium thickness did not differ between the L and H treatments (P = 0.46), tended to be higher for H+SB than for H (P = 0.09) but did not differ between H+TB and H (P = 0.61). The expression of downregulated in adenoma was higher for L than for H treatments (P = 0.03) but was not affected by SB or TB supplementation (P ≥ 0.26). In the ventral rumen, the mucosa surface and epithelium thickness were lower for L than for H treatments (P < 0.01), were or tended to be higher for H+SB than for H (P ≤ 0.06) but did not differ between H+TB and H (P ≥ 0.26). The expression of monocarboxylate transporter 1 was lower for L than for H treatments (P = 0.02) but was not affected by SB or TB supplementation (P ≥ 0.28). The expression of putative anion transporter-1 and downregulated in adenoma did not differ between the L and H treatments (P ≥ 0.76); however, expression of the former tended to be higher and the latter tended to be lower for H+SB than for H (P ≤ 0.09), whereas no differences were observed between H+TB and H (P ≥ 0.14). In summary, SB supplementation, but not TB supplementation, in a high-concentrate diet stimulated ruminal epithelium growth and affected short-chain fatty acid transporters expression in the ruminal epithelium.

The roles of short-chain fatty acids derived from colonic bacteria fermentation of non-digestible carbohydrates and exogenous forms in ameliorating intestinal mucosal immunity of young ruminants

Short-chain fatty acids (SCFA) are a class of organic fatty acids that consist of 1 to 6 carbons in length. They are primary end-products which arise from non-digestible carbohydrates (NDC) fermentation of colonic bacteria. They are the fundamental energy sources for post-weaning ruminants. SCFA represent the major carbon flux of diet through the gut microbiota to the host. They also play a vital role in regulating cell expansion and gene expression of the gastrointestinal tract (GIT). Recently, remarkable progresses have been made in understanding the immunomodulatory effects of SCFA and their interactions with the host. The processes involved in this study encompassed inflammasome activation, proliferation of lymphocytes, and maturation of intestinal mucosal immunity maturation. It is important to note that the establishment and maturation of intestinal mucosal immune system are intricately connected to the barrier function of intestinal epithelial cells (IEC) and the homeostasis of gut microbiota. Thus, insights into the role of SCFA in enteric mucosal immunoreaction of calves will enhance our understanding of their various regulatory functions. This review aims to analyze recent evidence on the role of SCFA as essential signaling molecules between gut microbiota and animal health. Additionally, we provide a summary of current literature on SCFA in intestinal mucosal immune responses of dairy calves.