Przewalskia tangutica improve rumen microbial community structure and promote rumen fermentation in sheep grazing on sown pastures

Przewalskia tangutica supplementation significantly increased average daily gain (ADG, P < 0.001) and reduced feed conversion ratio (FCR, P < 0.001), with the HP group exhibiting the highest ADG (139.94 g/d). Total volatile fatty acid (VFA) concentrations, along with acetate, isobutyrate, and butyrate levels, were significantly elevated in treatment groups compared to CON (P < 0.001), with HP showing the highest total VFA (93.74 mM). Digestive enzyme activities, including amylase (AMS), lipase (LPS), cellulase, and protease (PDH), were significantly enhanced in supplemented groups (P < 0.05). While bacterial alpha-diversity remained unaffected, beta-diversity indicated compositional shifts, with increased abundances of Verrucomicrobiota, Proteobacteria, and Fibrobacterota in treated groups (P < 0.05). Fungal diversity was significantly higher in the HP group (P < 0.05), with reduced Cladosporium abundance correlating with improved fiber degradation. Microbial co-occurrence networks revealed a shift towards balanced interactions in treated groups. Correlation analyses confirmed significant associations between microbial taxa, VFAs, and enzyme activities, underscoring the role of Przewalskia tangutica in modulating rumen function. These findings suggest that Przewalskia tangutica supplementation enhances rumen fermentation and sheep performance under saline-alkali grazing conditions through targeted microbial and enzymatic modulation, offering a sustainable feed additive strategy for challenging environments.