Clinical animal nutrition and molecular pathophysiology of periparturient disorders in ruminants: a comprehensive review

The transition period, extending from three weeks before the expected date of parturition to three weeks after parturition, represents the most metabolically challenging phase in the productive life of ruminants. During this period, rapid physiological adaptations associated with the onset of lactation frequently result in negative energy balance, oxidative stress, immune suppression and endocrine alterations, thereby predisposing animals to multiple interrelated metabolic disorders. This review comprehensively examines the molecular pathophysiology of major periparturient disorders, including hypocalcemia, ketosis, downer cow syndrome, subacute ruminal acidosis (SARA), laminitis, displaced abomasum, retained fetal membranes and periparturient mastitis. Emphasis is placed on the central role of metabolic inflammation, dysregulated calcium and energy homeostasis, altered growth hormone–insulin signalling, excessive mobilization of non-esterified fatty acids, ketogenesis, oxidative stress and impaired neutrophil function in disease pathogenesis. The review further highlights the application of clinical animal nutrition as a preventive and therapeutic strategy through dietary cation–anion difference (DCAD) manipulation, immunonutrition, antioxidant supplementation, rumen-protected nutrients and targeted mineral and vitamin supplementation to improve metabolic adaptation and immune competence during the transition period. Recent advances in metabolic biomarkers, including non-esterified fatty acids (NEFA), β-hydroxybutyrate (BHB) and inflammatory mediators, are discussed for early disease prediction and monitoring. Integrating molecular understanding with evidence-based nutritional management offers an effective approach to reducing disease incidence, improving animal welfare, enhancing reproductive efficiency and sustaining dairy productivity. Future research should focus on precision nutrition, biomarker-guided intervention and systems biology approaches to optimize transition cow health under modern production systems.