Probiotics Modulate the Ruminal Microbiome and Metabolite Availability to Enhance Rumen Barrier Function and Growth Performance in Goats Fed a High-Concentrate Diet.

Abstract

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.