Probiotics Modulate the Ruminal Microbiome and Metabolite Availability to Enhance Rumen Barrier Function and Growth...

The purpose of this study was to evaluate the effects of probiotics supplementation on goats fed a high-concentrate diet in terms of growth performance, rumen fermentation, microbiome and metabolite, and barrier function. Twelve 5-month-old goats (22.74 ± 0.31 kg) were randomly assigned to two groups. The control group (CON) was given a basal diet, whereas the experimental group (PRB) was provided with a diet supplemented with 2 g/kg of a probiotics for 60 days. The results indicated that the final weight (FW) and average daily gain (ADG) were significantly increased in the PRB group compared to the CON group (p < 0.05). Rumen fluid in the PRB group showed significantly elevated levels of butyrate, ammonia nitrogen, propionate, acetate, and total volatile fatty acids, with a significantly reduced acetate/propionate (p < 0.05). Additionally, the PRB group demonstrated significant increases in rumen papilla width and density of gastric papillae (p < 0.05). The mRNA relative expression of tight junction proteins Claudin-4, Claudin-1, Occludin, and ZO-1 in the rumen epithelium was significantly upregulated (p < 0.05). Furthermore, the mRNA relative expression of the anti-inflammatory factor IL-10 was significantly elevated, whereas the pro-inflammatory factors IL-1β and TNF-α were significantly reduced (p < 0.05). 16S rDNA sequencing revealed enrichment of beneficial microbes, such as Lachnospiraceae_NK4A136_group, Christensenellaceae_R-7_group, Monoglobus, Parabacteroides, Bacteroides, and Roseburia, which promoted fiber degradation and volatile fatty acid production. Elevated metabolites, including 2-lysophosphatidylcholin, PC(18:0/0:0), tryptophol, 5-hydroxy-6-methoxyindole glucuronide, and mevalonic acid, contribute to epithelial repair, barrier function, and fermentation. Additionally, 4-nitrocatechol was associated with improved rumen papillae structure and anti-inflammatory effects. In conclusion, probiotics supplementation enhanced rumen fermentation, microbial composition, and barrier function while alleviating inflammation, ultimately improving growth performance and rumen health in goats on a high-concentrate diet.