Dietary supplementation with Bupleuri Radix reduces oxidative stress occurring during growth by regulating rumen microbes and metabolites
Oxidative stress (OS) in ruminants is closely associated with disease, thus improving antioxidant capacity is an important strategy for maintaining host health. Bupleuri Radix (BR) could significantly improve host health and stress levels. However, the clear antioxidant mechanism of function of BR remains unknown. In this study, LC-MS metabolomics combined with 16 S rRNA gene sequencing was used to study the effects of BR on rumen microbiota and metabolites in weaned lambs, and Spearman correlation analyses of rumen microbiota, metabolites, and OS were performed to investigate the mechanism of BR's antioxidant effects. Our findings indicated that as lambs grow, levels of OS and antioxidant capacity increase dramatically, and that providing BR to lambs enhances antioxidant capacity while decreasing OS. Rumen microbiota has a strong relationship to OS, with total antioxidant capacity (T-AOC) showing a significant negative correlation with Succiniclasticum and a positive correlation with Ruminococcus. Importantly, the Chao1 index was significantly negatively correlated with Malondialdehyde (MDA) and positively correlated with Superoxide Dismutase (SOD) and T-AOC. The results of metabolomics and Spearman analysis of rumen contents revealed the screening of two biomarkers associated to the antioxidant effects of BR, namely 5,6-DHET and LPA (a-25:0/0:0), and a substantial connection was identified between rumen metabolites concentration and OS. Five metabolic pathways, including glycerolipid, glutathione, nucleotide, D-amino acid, and inositol phosphate metabolism, may have a role in OS. The integrated results indicate that rumen microbiota and metabolites are strongly related to OS, and that BR is responsible for reducing oxidative stress and improving antioxidant capacity in post-weaned lambs. These findings provide new strategies to reduce OS occurring during lamb growth.