Impact of Nutrient Composition on Rumen Microbiome Dynamics and Roughage Degradation

Abstract

Background: Ruminant animals such as goats rely on rumen microbial communities to degrade fibrous nutrients from roughages, facilitating their growth and development. This study investigates dynamic shifts in surface-attached rumen microbes in representative roughages: rice straw (RS), bamboo shoot sheet (BSS), and alfalfa (ALF). Four 14-month-old Min Dong goats with rumen fistulas were used, and the roughages were assessed at 4 h, 12 h, 24 h, 36 h, 48 h, and 72 h intervals. Microbiome composition and function were revealed through 16S rRNA and metagenomics sequencing. Results: Prevotella and Treponema were the predominant genera in roughage degradation. Nutritional composition and tissue structure of roughages affected microbial attachment, causing variations in nutrient degradation rates. Microbials related to dry matter (DM) and crude protein (CP) degradation were abundant in early fermentation stages (4-12h) but decreased over time, while fiber-degrading microbials increased after 24 hours. Surface-attached microbials produced enzymes such as β-Glucosidase (BG), Endo-β-1,4-glucanase (C1), Exo-β-1,4-glucanase (Cx), and Neutral xylanase (NEX), with enzymatic activity correlating with the fiber content of the roughages. Conclusions: These findings advance our understanding of microbial roles in ruminant nutrition and digestion. The interaction between microbial communities and rumen fermentation is pivotal for understanding collaborative gene encoding by goat rumen microbiota, which is critical for fiber degradation.