Rumen microbes affect the somatic cell counts of dairy cows by modulating glutathione metabolism

Abstract

Healthy mammary glands are essential for high-quality milk production in the dairy industry. The relationship between somatic cell counts (SCCs), rumen fermentation, and microbiota interactions remains unclear. This study integrated physiological indicators, high-throughput 16S rRNA gene sequencing, and metagenomics data analysis to investigate the mechanisms linking rumen microbes and mastitis and to evaluate the changes in milk production and serum cytokine levels in cows with low (L-SCC) and high (H-SCC) somatic cell counts. Compared with the L-SCC group, the H-SCC group exhibited significantly lower lactose and fat contents in milk, reduced rumen fermentation product levels, and increased abundances of Bacteroidetes, Firmicutes, Lachnospiraceae, Prevotella, and Rumiclostridium. Elevated serum levels of IgG2, IgM, IL-1β, IL-6, and TNF-α in the H-SCC group indicated inflammation and rumen microbiota dysbiosis. Functional analysis of microbial communities revealed significant enrichment in pathways related to glutathione metabolism, thyroid hormone synthesis, hypertrophic cardiomyopathy (HCM), the phosphotransferase system (PTS), the P53 signaling pathway, and the Jak-STAT signaling pathway. Correlation network analysis showed that changes in bacterial families, such as Rikenellaceae, Muribaculaceae, and Prevotellaceae, were associated with cytokines, rumen fermentation, and milk quality. The study highlights the interaction between rumen microbiota homeostasis and mammary gland health, indicating that rumen fermentation status influences serum inflammation and milk quality. Modulating rumen fermentation to enhance mammary gland immune function presents a viable strategy for sustainable dairy industry development with long-lived, highly productive cows. Copyright © 2025 Zhang et al.