** AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** EACH YEAR, OVER 3 MILLION COWS THAT TRANSITION FROM LATE GESTATION TO EARLY LACTATION SUCCUMB TO ECONOMICALLY IMPORTANT DISEASES SUCH AS MASTITIS OR METRITIS, ADVERSELY AFFECTING THE PROFITABILITY OF THE US DAIRY INDUSTRY. MASTITIS ALONE COSTS US DAIRY PRODUCERS APPROXIMATELY $2BILLION IN LOST PROFITS ANNUALLY. A KEY FACTOR RESPONSIBLE FOR THE DEVELOPMENT OF TRANSITION COW HEALTH DISORDERS IS OXIDATIVE STRESS (OS), WHICH RESULTS FROM THE IMBALANCE BETWEEN THE PRODUCTION OF REACTIVE OXYGEN SPECIES (ROS) DURING TIMES OF HIGH METABOLIC DEMANDS AND THE AVAILABILITY OF ANTIOXIDANT DEFENSES THAT ARE NEEDED TO REDUCE ROS-INDUCED CELLULAR DAMAGE AND SUBSEQUENT LOSS OF FUNCTION. ADULT DAIRY COWS EXPERIENCE OS AROUND THE TIME OF CALVING, WHICH DIMINISHES IMMUNE CELLS' FUNCTIONAL CAPABILITIES AND INCREASE DISEASE SUSCEPTIBILITY. HOWEVER, A MAJOR OBSTACLE IN MITIGATING THE DETRIMENTAL IMPACT OF OS ON TRANSITION COW HEALTH IS THE LACK OF AN ACCURATE WAY TO ASSESS THE AMOUNT OF OXIDATIVE INJURYTHAT IS ASSOCIATED WITH SUBSEQUENT DISEASES. IN HUMAN MEDICINE, PLASMA ISOPROSTANE (ISOP) CONCENTRATIONS ARE CONSIDERED THE GOLD STANDARD FOR ASSESSING OS ASSOCIATED WITH DISEASE RISK. IN VETERINARY MEDICINE, HOWEVER, WE LACK CRITICAL THRESHOLDS FOR OS BIOMARKERS. THUS, THIS PROJECT WILL EXPLORE THE USEFULNESS OF ISOP AS BIOMARKERS OF OS IN PERIPARTURIENT CATTLE AND HOW MANIPULATING ISOP PRODUCTION CAN ENHANCE DAIRY COW HEALTH. A BETTER UNDERSTANDING OF HOW IMMUNITY CAN BE ENHANCED THROUGH NUTRITIONAL INTERVENTIONS THAT CONTROL OS MAY LEAD TO IMPROVED DISEASE PREVENTION STRATEGIES, A REDUCTION OF THE ANTIMICROBIAL USAGE, AND OPTIMIZED PRODUCTION EFFICIENCY IN THE DAIRY INDUSTRY.