THE US DAIRY INDUSTRY RECOGNIZES THAT ANIMAL HEALTH PLAYS AN ESSENTIAL ROLE IN FEED EFFICIENCY AND MILK QUALITY, AS EVIDENCED BY THE WEALTH OF RESEARCH CONDUCTED ON THIS TOPIC IN THE LAST TWO DECADES. A MAJOR CHALLENGE IN DAIRY COW HEALTH IS THE TRANSITION FROM LATE PREGNANCY TO LACTATION. THIS STRESSFUL PERIOD IS CHARACTERIZED BY SUBSTANTIAL METABOLIC AND PHYSIOLOGICAL CHANGES DUE TO ENERGY DEMANDS FOR FETAL GROWTH AND LACTATION. THIS TRANSITION IS OFTEN CORRELATED WITH A SIGNIFICANT INCREASE IN HEALTH DISORDERS OCCURRING WITHIN THE FIRST WEEKS AFTER BIRTH. THESE HEALTH DISORDERS CAN SEVERELY REDUCE MILK PRODUCTION, REPRODUCTIVE PARAMETERS, AND CAUSE WELFARE ISSUES THAT CAN LEAD TO DEATH OR REMOVAL OF COWS FROM THE HERD. THESE HEALTH DISORDERS CAN HAVE A TREMENDOUS ECONOMIC IMPACT ON DAIRY FARMS AND SUBSEQUENTLY MAKE THE DAIRY INDUSTRY AT LARGE LESS ENVIRONMENTALLY SUSTAINABLE.OXIDATIVE STRESS IS A BIOLOGICAL CONDITION COMMON TO ALL MULTICELLULAR ORGANISMS, AND IN HUMANS, IT HAS BEENASCRIBED AS AN UNDERLYING FACTOR FOR SEVERALDISEASES, INCLUDING PARKINSON'S, ALZHEIMER'S, AND CANCER, AMONG OTHERS. OXIDATIVE STRESS IS AN IMBALANCE BETWEEN OXIDANTS, ALSO CALLED REACTIVE OXYGEN SPECIES, AND ANTIOXIDANTS SUCH AS GLUTATHIONE. DAIRY COWS ARE COMMONLY EXPOSED TO THE HIGHEST LEVELS OF OXIDATIVE STRESS DURING THE TRANSITION FROM PREGNANCY TO LACTATION. THEREFORE, THE AIM OF THIS STUDY IS TO UNDERSTAND THE CRUCIAL ROLE GLUTATHIONE PLAYS DURING THE TRANSITION PERIOD OF DAIRY COWS BY COMPARING COWS WITH HIGH GLUTATHIONE AGAINST LOW-GLUTATHIONE COWS.TO REACH THIS GOAL, WE WILL DETERMINE GLUTATHIONE CONCENTRATIONS IN LIVER BIOPSIES SAMPLES FROM DAIRY COWS TAKEN BEFORE CALVING. WE WILL USE THIS DATA TO PERFORM A RETROSPECTIVE ANALYSIS BASED ON COWS WITH HIGH VERSUS LOW LIVER GLUTATHIONE LEVELS. ADDITIONALLY, WE WILL PERFORM CONTEMPORARY GENE EXPRESSION AND WESTERN BLOT ANALYSES TO GIVE US A CLEARER PICTURE OF THE TRANSCRIPTIONAL AND METABOLIC STATUS OF ENZYMES RELATED TOGLUTATHIONE SYNTHESIS AND STORAGE IN THE LIVER OF TRANSITION DAIRY COWS. WE WILL ALSO COLLECT BLOOD SAMPLES TO MONITOR CONCENTRATIONS OF GLUTATHIONE, BIOMARKERS OF OXIDATIVE STRESS, LIVER FUNCTION, INFLAMMATION, AS WELL AS HORMONES SUCH AS INSULIN AND CORTISOL. THIS INFORMATION WILL GIVE US A BROADER UNDERSTANDING OF HOW ADEQUATE RESERVES OF LIVER GLUTATHIONE MAY IMPACT THE ANIMAL AT A SYSTEMIC LEVEL. IN ADDITION, WE WILL CORRELATE PERFORMANCE PARAMETERS SUCH AS MILK YIELD, FEED INTAKE, AND BODY CONDITION SCORE IN TRANSITION COWS WITH HIGH AND LOW LIVER GLUTATHIONE.COLLECTIVELY, DATA FROM THIS STUDYWILL ALLOW US TO DELINEATE THE RELATIONSHIPS BETWEEN GLUTATHIONE PRECURSORS AND GLUTATHIONE STORAGE IN THE LIVER OF DAIRY COWS UNDER STRESS CONDITIONS. UNDERSTANDING THE MECHANISMS THAT REGULATE GLUTATHIONE STORAGE IN TRANSITION DAIRY COWS WILL ENABLE US TO DEVISE NUTRITIONAL AND MANAGEMENT STRATEGIES FOR DAIRY FARMERS AND DAIRY CONSULTANTSTO PREVENT OXIDATIVE STRESS AND THEREBY IMPROVE ANIMAL HEALTH AND PERFORMANCE.