Perilla frutescens (L.) Britt., an annual herbaceous plant, has antibacterial, anti-inflammation, and antioxidant properties. To understand the effects of P. frutescens leaf on the ruminal microbial ecology of cattle, Illumina MiSeq 16S rRNA sequencing technology was used. Fourteen cows were used in a randomized complete block design trial. Two diets were fed to these cattle: a control diet (CON); and CON supplemented with 300 g/d P. frutescens leaf (PFL) per cow. Ruminal fluid was sampled at the end of the experiment for microbial DNA extraction. Overall, our findings revealed that supplementation with PFL could increase ruminal fluid pH value. The ruminal bacterial community of cattle was dominated by Bacteroidetes, Firmicutes, and Proteobacteria. The addition of PFL had a positive effect on Firmicutes, Actinobacteria, and Spirochaetes, but had no effect on Bacteroidetes and Proteobacteria compared with the CON. The supplementation with PFL significantly increased the abundance of Marvinbryantia, Acetitomaculum, Ruminococcus gauvreauii, Eubacterium coprostanoligenes, Selenomonas_1, Pseudoscardovia, norank_f__Muribaculaceae, and Sharpea, and decreased the abundance of Treponema_2 compared to CON. Eubacterium coprostanoligenes, and norank_f__Muribaculaceae were positively correlated with ruminal pH value. It was found that norank_f__Muribaculaceae and Acetitomaculum were positively correlated with milk yield, indicating that these different genera are PFL associated bacteria. This study suggests that PFL supplementation could increase the ruminal pH value and induce shifts in the ruminal bacterial composition.

Gut microbes play a crucial role in transforming primary bile acids (BAs) into secondary forms, which influence systemic metabolic processes. The rumen, a distinctive and critical microbial habitat in ruminants, boasts a diverse array of microbial species with multifaceted metabolic capabilities. There remains a gap in our understanding of BA metabolism within this ecosystem. Herein, through the analysis of 9371 metagenome-assembled genomes and 329 cultured organisms from the rumen, we identified two enzymes integral to BA metabolism: 3-dehydro-bile acid delta4,6-reductase (baiN) and the bile acid:Na + symporter family (BASS). Both in vitro and in vivo experiments were employed by introducing exogenous BAs. We revealed a transformation of BAs in rumen and found an enzyme cluster, including L-ribulose-5-phosphate 3-epimerase and dihydroorotate dehydrogenase. This cluster, distinct from the previously known BA-inducible operon responsible for 7α-dehydroxylation, suggests a previously unrecognized pathway potentially converting primary BAs into secondary BAs. Moreover, our in vivo experiments indicated that microbial BA administration in the rumen can modulate amino acid and lipid metabolism, with systemic impacts underscored by core secondary BAs and their metabolites. Our study provides insights into the rumen microbiome’s role in BA metabolism, revealing a complex microbial pathway for BA biotransformation and its subsequent effect on host metabolic pathways, including those for glucose, amino acids, and lipids. This research not only advances our understanding of microbial BA metabolism but also underscores its wider implications for metabolic regulation, offering opportunities for improving animal and potentially human health.

Background: Rumen is a natural fermentation system and the microorganisms inside can effectively utilize plant bioresource and interact with host metabolism. Here, analysis of rumen microbiome, together with animal performance and serum metabolism in a lamb model were performed to identify the potential use of mulberry leaf silage (MS) to replace alfalfa silage (AS) as a new functional feed resource and to mining the novel specific mulberry leaf associated rumen bacteria interact with host metabolism. Results: The lambs fed with MS diet showed improved antioxidant capacity and immune function compared to those fed AS diet. The MS diet significantly altered rumen microbiota α- and β-diversity and taxonomic composition. Microbial analysis revealed that Bifidobacterium, Lactobacillus and Schwartzia were enhanced, and Ruminococcaceae UCG-010 and Lachnospiraceae_XPB1014_group were down-regulated in the rumen of MS group. A strong association was also found between these rumen microbial taxa and host antioxidant and immunomodulatory capacity. Conclusion: These findings indicated that mulberry leaf silage can be a high-quality feed source or bioactive pharmaceutical that is responsible for ruminant’s health benefits. The modified rumen microbial community by mulberry leaf silage were associated with the enhanced antioxidant capacity and immunomodulatory of lambs.

This study was evaluated the effects of different carbohydrate sources on the fermentation profiles, chemical compositions, and correlation of fermentation profiles and chemical compositions with water-soluble carbohydrate (WSC) of alfalfa (Medicago sativa) silage. Alfalfa was harvested at early flowering stage from the third cutting in September 2018, wilted to 32% dry matter (DM) and chopped into 1–2 cm pieces. Treatments included the addition of pectin (PEC), starch (STA; powdered corn), molasses (MOL), and fructose (FRU), as well as distilled water as a control (CON). Afterward, 300 g of prepared alfalfa was packed into polyethylene bags, vacuumed, and sealed, after which they were stored at room temperature for 1, 3, 7, 15, and 30 d. FRU and PEC additions resulted in desirable fermentation profiles and chemical compositions throughout the ensiling period. FRU and PEC rapidly decreased the pH and increased Fleig’s point, exhibiting lower pH and higher Fleig’s point from 3 d to the end of ensiling. Acetic acid (AA), propionic acid (PA) and ammonia nitrogen (AN) contents of FRU and PEC were lower at 30 d after ensiling. Higher lactic acid (LA) contents were found in FRU and PEC from 7 d to the end of ensiling and higher LA:AA ratios from 15 d to the end of ensiling. Butyric acid (BA) was not detected at any point during the ensiling period. Additives exhibited higher DM content from 7 to 30 d after ensiling. The WSC content decreased as the number of ensiling days increased and was stable from 15 d to the end of ensiling. PEC, STA, and FRU exhibited higher WSC than CON. FRU and PEC improved the fermentation quality throughout the ensiling period. Thus, FRU and PEC or related agricultural byproducts may offer alternative additives for improving the alfalfa silage fermentation profile.