APPROXIMATELY 75% OF DISEASE INCIDENCE IN DAIRY COWS OCCUR WITHIN THE FIRST 30 DAYS OF LACTATION, WHICH LEADS TO REDUCED MILK PRODUCTION, INCREASED ANTIMICROBIAL USAGE, AND PREMATURE CULLING. EARLY LACTATION COWS ARE UNIQUE DUE TO THEIR SUBSTANTIAL NEED FOR METABOLIZABLE ENERGY TO SUPPORT THE ONSET OF LACTATION AND THEIR ALTERED IMMUNE FUNCTION FOLLOWING PARTURITION. DESPITE RIGOROUS RESEARCH AND PREVENTATIVE MEASURES, GREATER THAN 50% OF EARLY LACTATION COWS LIKELY EXPERIENCE AT LEAST ONE SUBCLINICAL DISEASE. IT IS EVIDENT THE FIELD REQUIRES GREATER UNDERSTANDING OF EARLY LACTATION COW BIOLOGY. THE BAUMGARD LAB STUDIES CONSEQUENCES OF IMMUNE ACTIVATION IN LIVESTOCK. MY PRELIMINARY RESEARCH DISCOVERED EARLY LACTATION COWS HAVE A MORE SEVERE IMMUNE RESPONSE TO INFECTION THAN COWS IN LATER LACTATION, AND DATA INDICATE THERE IS 1) ENHANCED INFLAMMATION AND 2) ALTERED METABOLIC FLEXIBILITY, WHICH IS REQUIRED FOR SUCCESSFUL IMMUNE RESPONSE. THE PROJECT PROPOSED AIMS TO ELUCIDATE HOW THE UNIQUE METABOLIC STATE IN EARLY LACTATION IMPACTS IMMUNE FUNCTION DURING INFECTION. BIOPSIES OF LIVER, MUSCLE, AND ADIPOSE TISSUE WILL BE COLLECTED FROM EARLY AND LATE LACTATION DAIRY CATTLE DURING INDUCED MASTITIS TO UNDERSTAND HOW LACTATION STAGE AFFECTS METABOLIC FLEXIBILITY FOLLOWING IMMUNE ACTIVATION. THIS PROJECT WILL ADVANCE CURRENT UNDERSTANDING OF EARLY LACTATION COW BIOLOGY BY POTENTIALLY FOSTERING NEW PREVENTATIVE AND TREATMENT SOLUTIONS TO IMPROVE COW HEALTH AND SUSTAINABILITY.