Lactate in ruminant health: metabolic roles and the emerging significance of lactylation

In ruminants, lactate metabolism is closely integrated with rumen fermentation, metabolic adaptation, and redox homeostasis under both physiological and pathological conditions. Under metabolic stress, alterations in lactate production, transport, and utilization may support tissue adaptation, but may also contribute to metabolic dysfunction and disease. As an emerging epigenetic modification, lactylation has been proposed as a mechanistic link between lactate metabolism and gene regulation, with lactate serving as a putative precursor. In this review, we summarize the dual roles of lactate in ruminant health and stress responses, evaluate the feasibility of lactate as a precursor for lactylation, and discuss the potential mechanisms and biological significance of lactylation in metabolic regulation and disease pathogenesis. Because direct evidence in ruminants remains limited, findings from non-ruminant models are considered only where they provide relevant mechanistic support. Overall, this review highlights current knowledge, major uncertainties, and key priorities for future mechanistic studies of lactate metabolism and lactylation in ruminants.