Enhancing sheep rumen health with Przewalskia tangutica: boosting fermentation and microbial diversity in saline-alkali sown pastures.

Abstract

Background: Livestock grazing on saline-alkali pastures frequently encounter nutritional challenges due to inadequate forage quality and imbalanced rumen function. Phytogenic feed additives, which are abundant in bioactive compounds such as tropane alkaloids and flavonoids, have demonstrated potential in enhancing rumen fermentation and improving animal performance. Przewalskia tangutica, a desert plant rich in these compounds, remains largely unexplored concerning its effects on microbiota and metabolism in sheep under saline-alkali conditions. This study aims to evaluate the impact of graded supplementation of Przewalskia tangutica on rumen fermentation, microbial dynamics, digestive enzyme activity, and growth performance in sheep grazing on degraded saline-alkali pastures.

Results: Supplementation with Przewalskia tangutica significantly increased the average daily gain (ADG, P < 0.001) and reduced the feed conversion ratio (FCR, P < 0.001). The high-dose group (HP) exhibited the highest ADG at 139.94 g/d. Additionally, the concentrations of total volatile fatty acids (VFAs), including acetate, isobutyrate, and butyrate, were significantly elevated (P < 0.001), peaking at 1.46 mmol/L in the HP group. Furthermore, the activities of amylases, lipase, cellulase, and protease increased significantly (P < 0.05). While the bacterial alpha diversity remained unchanged, beta diversity analysis revealed structural shifts characterized by increased abundances of Verrucomicrobiota, Proteobacteria, and Fibrobacterota (P < 0.05). Fungal diversity also increased under the HP treatment (P < 0.05), whereas a reduction in Cladosporium abundance was correlated with enhanced fiber degradation. Moreover, microbial co-occurrence networks demonstrated more balanced interactions in the treated groups, with significant correlations among taxa, enzymes, and VFAs.

Conclusions: Przewalskia tangutica improves rumen fermentation and sheep performance in saline-alkali environments through targeted modulation of microbial communities and enzymatic activity, particularly at the high dose, significantly improved sheep growth performance by increasing average daily gain and reducing the feed conversion ratio, suggesting a sustainable strategy for livestock production in challenging ecosystems.