Ruminal microbial dysbiosis induces mastitis in dairy goats by activating oxidative stress and ferritinophagy-ferroptosis

Recent studies indicate that ruminal microbiota dysbiosis plays a significant role in the development of mastitis in ruminants, though the exact mechanisms remain incompletely understood. In this study, a high-concentration (HC) diet led to subacute ruminal acidosis (SARA) in dairy goats, as evidenced by prolonged daily periods of ruminal pH below 5.8. The HC group exhibited disrupted ruminal microbiota, elevated serum levels of LPS, TNF-α, and IL-1β, and a markedly increased milk somatic cell count (SCC) exceeding 500,000/mL, indicating mastitis. Ruminal microbiota transplantation (RMT) from HC goats induced mastitis in mice, which is associated with oxidative stress and ferritinophagy-ferroptosis. The administration of ferrostatin-1 (Fer-1) alleviated mastitis in mice. Further <i>in vitro</i> experiments showed that LPS dose-dependently triggered oxidative stress and ferritinophagy-ferroptosis in mouse mammary epithelial cells (MMECs). Collectively, HC diet-induced ruminal dysbiosis elevates systemic and mammary LPS levels, reduces antioxidant capacity, and activates oxidative stress and ferritinophagy-ferroptosis, ultimately leading to mastitis.