With the increasing demand for high-yield dairy production, the industry has widely adopted high-concentrate (HC) diets to enhance milk production. Studies have shown that HC diets reduce ruminal motility and fiber digestibility, leading to prolonged retention of fermentable substrates [1]. Excessive volatile fatty acid (VFA) accumulation overwhelms the rumen buffering capacity, causing a drop in pH < 5.8 for 3 h a day, which is a key diagnostic criterion for subacute ruminal acidosis (SARA) [2]. In ruminants with SARA, decreased rumen pH alters rumen microecology, in which rumen microbiota, as one of the important components, is affected in both its composition and abundance [[3], [4], [5]]. The Gram-negative bacteria were lysed to release lipopolysaccharide (LPS), the main virulence factor [6]. LPS damages rumen epithelium and increases its barrier permeability by disrupting the expression of tight junction protein (TJs) [7]. Free LPS enters the bloodstream, translocating to liver through the portal vein. As the primary detoxification and immune organ, the liver activates macrophages such as Kupffer cells to absorb and neutralize LPS after being stimulated, and then excreted with bile. Chronic LPS exposure impaires liver function. It can also spread LPS in the circulation [8,9], potentially inducing distal organs inflammation or systemic inflammatory response [10].

Ferroptosis is an iron-dependent, non-apoptotic form of programmed cell death, characterized by oxidative stress-induced lipid peroxidation and the production of large amounts of lipid reactive oxygen species (ROS) catalyzed by iron ions [11,12]. This process is tightly regulated by iron metabolism. Intracellular iron is stored in ferritin composed of ferritin light polypeptide 1 (FLT) and ferritin heavy polypeptide 1 (FHT) [13]. Ferritinophagy, a selective autophagy that regulates iron metabolism and maintains cellular iron homeostasis. Nuclear receptor coactivator 4 (NCOA4) directly binds to FTH, mediating intracellular ferritin transport to autophagic lysosomes for autophagic degradation and subsequent release of free iron [14,15]. Overactivation of ferritinophagy increases the unstable iron pool in the cell, catalyzes abnormal cell metabolism and excessive lipid peroxide production [[16], [17], [18]]. Concurrently, excessive intracellular iron deposition depletes glutathione (GSH) and reduces glutathione peroxidase 4 (GPX4) expression, impairing the antioxidant system. This leads to cell membrane collapse and rupture, ultimately triggering ferroptosis [19,20]. The correlation between SARA-induced liver injury mediated by rumen-derived LPS and the ferritinophagy-ferroptosis axis remains unclear. This study investigates whether rumen-derived LPS induces hepatic injury via oxidative stress mediated activation of the ferritinophagy-ferroptosis axis, providing insights into the molecular mechanism underlying HC diet induced SARA associated liver injury in ruminants.