Alleviation effects of niacin supplementation on beef cattle subjected to heat stress: A metagenomic insight

Under heat stress conditions, selenium nanoparticles promote lactation through modulation of rumen microbiota and metabolic processes in dairy goats

This study aimed to investigate the effects of dietary supplementation with Selenium nanoparticles (SeNPs) on lactation performance, rumen microbial communities, and metabolism in dairy goats under heat stress conditions. Twenty Guanzhong dairy goats with the same parity, similar lactation period (120 ± 15 days), and similar milk yield (1.20 ± 0.16 kg/day) were randomly divided into two groups, with 10 replicates in each group. The control group was fed a standard diet, while the experimental group was supplemented with 0.5 mg SeNPs/kg DM based on the standard diet. The pretrial period lasted for seven days, followed by a 30-day trial period. The results showed that dietary supplementation with SeNPs significantly increased milk yield, milk fat and lactose content in dairy goats, under heat stress conditions. SeNPs significantly altered the composition of the rumen microbiota, increasing the relative abundance of Prevotella and Ruminococcus while decreasing the relative abundance of Succiniclasticum. This enhanced the rumen's ability to degrade starch and fiber under heat stress conditions. Non-targeted metabolomic analysis revealed a total of 119 differential metabolites between the two groups, indicating changes in rumen metabolism. Further correlation analysis indicated that Rumen bacterium R-21 was positively correlated with propionate, while Ralstonia insidiosa was negatively correlated with γ-glutamylcysteine. Additionally, several differential microbes, including Succinivibrio dextrinosolvens, Rummeliibacillus pycnus, Ralstonia insidiosa, and Prevotella sp BP1-56, were significantly correlated with milk composition. In conclusion, dietary supplementation with SeNPs can positively impact milk yield, milk components, and metabolism in dairy goats by improving the composition of the rumen microbiota under heat stress conditions.

Effects of Key Rumen Bacteria and Microbial Metabolites on Fatty Acid Deposition in Goat Muscle

In this study, the fatty acid composition in the muscles of Hechuan white goats was correlated with the metabolome and metagenome of their rumen contents, and potential effects of the metabolites and microorganisms in the rumen on host muscle fatty acid deposition were analyzed. The results of the correlation analysis between the rumen content's metabolome and muscle fatty acid content showed that vitamin-B-related metabolites were significantly correlated with fatty acid content (p < 0.05). Most of these metabolites were positively correlated with stearic acid and negatively correlated with palmitic acid. In accordance with the level of fatty acid content, significant differences were found in the microbial species and abundance among groups at the species level. An abundance of Bacteroides, Ruminococcaceae P7, Eubacterium ruminant, and Prevotella in the rumen was significantly correlated with fatty acid content. These results provide data support for the development of targeted feeding management strategies to improve the quality of goat meat.

The effect of Phyllanthus emblica (Amla) fruit supplementation on the rumen microbiota and its correlation with rumen fermentation in dairy cows

Introduction

Medicinal plants, rich in phytochemicals like phenolic acids, flavonoids, and tannins, offer potential benefits in enhancing productivity, quality, and animal health. Amla fruit (Phyllanthus emblica) is one such plant with promising attributes. This study aimed to investigate the impact of fresh Amla fruit (FAF) supplementation on ruminal microbial composition and its correlation with rumen fermentation in lactating dairy cows.

Methods

The study employed a repeated crossover design involving eight ruminally cannulated mid-lactation Holstein dairy cows. Animals received varying levels of fresh Amla fruit supplementation (0, 200, 400, and 600 g/d).

Results

When 400 g/d of FAF was added to the diet, there was a significant increase in the relative abundance of Firmicutes (p = 0.02). However, at 200 g/d, the relative abundance of ruminal Bacteroidota was higher than the 0 and 400 g/d FAF supplementation (p < 0.01). LEfSe analysis identified distinct taxa, such as Clostridia vadinBB60 in the 200 g/d group, Oscillospiraceae in the 400 g/d group, and Elusimicrobium in the 600 g/d group. Notably, the random forest species abundance statistics identified Oscillospiraceae V9D2013 as a biomarker related to milk yield. Oscillospiraceae, Bacilli RF39, norank_f Prevotellaceae, and Bifidobacterium were positively correlated with ruminal total VFA and molar proportion of propionate, while Rikenellaceae RC9 gut group and Clostridia vadinBB60 were negatively correlated.

Discussion

FAF supplementation affects the abundance of beneficial microbes in a dose-dependent manner, which can improve milk yield, efficiency, rumen health, desirable fatty acids, and animal health.

Metagenomic sequencing identified microbial species in the rumen and cecum microbiome responsible for niacin treatment and related to intramuscular fat content in finishing cattle

Introduction

Niacin is one of the essential vitamins for mammals. It plays important roles in maintaining rumen microecological homeostasis. Our previous study indicated that dietary niacin significantly elevated intramuscular fat content (IMF) in castrated finishing steers. Whether niacin affects fat deposition by regulating the microbial composition and functional capacities of gastrointestinal microbiome has been unknown yet.

Methods

In this study, 16 castrated Xiangzhong Black cattle were randomly assigned into either control group fed with a basal concentrate diet (n = 8) or niacin group fed with a basal concentrate diet added 1000 mg/kg niacin (n = 8). Seven rumen samples and five cecum content samples were randomly collected from each of control and niacin groups for metagenomic sequencing analysis.

Results

A total of 2,981,786 non-redundant microbial genes were obtained from all tested samples. Based on this, the phylogenetic compositions of the rumen and cecum microbiome were characterized. We found that bacteria dominated the rumen and cecum microbiome. Prevotella ruminicola and Ruminococcus flavefaciens were the most abundant bacterial species in the rumen microbiome, while Clostridiales bacterium and Eubacterium rectale were predominant bacterial species in the cecum microbiome. Rumen microbiome had significantly higher abundances of GHs, GTs, and PLs, while cecum microbiome was enriched by CBMs and AAs. We found a significant effect of dietary niacin on rumen microbiome, but not on cecum microbiome. Dietary niacin up-regulated the abundances of bacterial species producing lactic acid and butyrate, fermenting lactic acid, and participating in lipid hydrolysis, and degradation and assimilation of nitrogen-containing compounds, but down-regulated the abundances of several pathogens and bacterial species involved in the metabolism of proteins and peptides, and methane emissions. From the correlation analysis, we suggested that niacin improved nutrient digestion and absorption, but reduced energy loss, and Valine, leucine and isoleucine degradation of rumen microbiome, which resulted in the increased host IMF.

Conclusion

The results suggested that dietary manipulation, such as the supplementation of niacin, should be regarded as the effective and convenient way to improve IMF of castrated finishing steers by regulating rumen microbiome.

Protective Effects of Niacin on Rumen Epithelial Cell Barrier Integrity in Heat-Stressed Beef Cattle

The present study investigates the theoretical basis for maintaining normal physiological functions in heat-stressed beef cattle by exploring the effects of niacin supplementation on the permeability of the rumen epithelial cell barrier. Herein, 12 Jinjiang bulls with an average weight of approximately 400 ± 20.0 kg were randomly divided into three groups, thermoneutral (TN), heat-stressed (HS), and heat-stressed niacin-supplemented (HN) groups, with 4 bulls in each group. The experiment spanned 70 days, and the plasma concentrations of D-lactic acid, diamine oxidase (DAO), lipopolysaccharides (LPSs), and inflammatory cytokines were analyzed. Additionally, we assessed the gene expression of tight junction proteins to understand the effect of niacin supplementation on heat-stressed beef cattle. Our results revealed that heat stress significantly increased the D-lactic acid and LPS levels in beef cattle plasma on days 30 and 45 of the experiment (p < 0.05). Moreover, it led to a significant rise in DAO levels on day 30 (p < 0.05). Niacin supplementation significantly reduced the LPS levels on day 30 (p < 0.05). Heat stress significantly elevated the plasma concentrations of inflammatory cytokines interleukin-1β (IL-1β), IL-2, IL-6, and tumor necrosis factor-α (TNF-α) (p < 0.05), while reducing the IL-4 concentration (p < 0.05). However, niacin supplementation effectively mitigated the concentrations of these inflammatory factors by reducing IL-1β, IL-2, IL-6, and TNF-α concentrations and increasing IL-4 concentrations. The mRNA expressions of tight junction proteins zonula occluden-1 (ZO-1), claudin-1, claudin-4, and claudin-7 were significantly downregulated (p < 0.05) in the HS group compared to those in the TN group, and those of ZO-1 and occludin were significantly upregulated (p < 0.05) in the HN group compared to those in the HS group. Notably, no significant differences were observed in ruminal papillae length and width among the studied groups (p > 0.05). Our findings indicate that heat stress adversely impacted the tight junction structure of the rumen epithelium, leading to a significant reduction in the expression of tight junction protein mRNA. Consequently, heat stress impaired the rumen mucosal barrier function, resulting in increased intestinal permeability. The mechanism underlying this effect may be associated with the decreased expression of tight junction protein genes in the rumen epithelial cells. However, niacin supplementation mitigated the detrimental effects of heat stress on intestinal permeability in beef cattle and increased the expression of tight junction protein genes in the rumen epithelium, thereby effectively protecting the rumen barrier in heat-stressed beef cattle. These results highlight the potential of nicotinic acid as a protective agent against the negative impacts of heat stress on intestinal integrity in beef cattle.