**AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** OVER THE LAST DECADE INCREASED EMPHASIS HAS BEEN PLACED ON IMPROVING OUR UNDERSTANDING OF RUMINANT LIPID DIGESTION ANDMETABOLISM IN ORDER TO ENHANCE DAIRY COW PRODUCTIVITY, ANIMAL HEALTH, AND THE QUALITY OF DAIRY PRODUCTS FOR CONSUMERS. OUR PROJECTS FOCUS IS ON THE PERIOD AROUND CALVING AND THE INITIATION OF MILK PRODUCTION (THE PERIPARTURIENT PERIOD). THIS PERIOD IS CHALLENGING FOR DAIRY COWS AS ENERGY AND NUTRIENT INTAKE DO NOT MEET REQUIREMENTS FOR MAINTENANCE, GROWTH, AND MILK SYNTHESIS. AS A RESULT, COWS EXPERIENCE NEGATIVE ENERGY BALANCE DURING EARLY LACTATION THAT IS FURTHER AGGRAVATED BY REDUCED FEED INTAKE. COWS SUCCESSFULLY ADAPT TO NEGATIVE ENERGY BALANCE WHEN THE RELEASE OF FATTY ACIDS FROM BODY FAT IS LIMITED TO CONCENTRATIONS THAT CAN BE FULLY USED FOR ENERGY NEEDS. EXCESSIVE MOBILIZATION OF BODY RESERVES AROUND PARTURITION ARE ASSOCIATED WITH POOR LACTATION PERFORMANCE AND INCREASED INCIDENCE OF DISEASES. OUR LONG-TERM GOAL IS TO DEVELOP STRATEGIES FOR FEEDING PERIPARTURIENT DAIRY COWS TO INCREASE THE YIELD AND EFFICIENCY OF MILK PRODUCTION WHILE OPTIMIZING BODY CONDITION AND HEALTH. OUR OBJECTIVE OF THIS PROJECT IS TO DETERMINE THE ROLE OF DIETARY OLEIC ACID ON ADIPOSE TISSUE METABOLISM, ENERGY PARTITIONING, AND MILK PRODUCTION OF PERIPARTURIENT DAIRY COWS. BASED ON OUR PRELIMINARY DATA, WE HYPOTHESIZE THAT DIETARY OLEIC ACID REGULATES LIPOGENESIS AND INSULIN SENSITIVITY IN ADIPOSE TISSUE OF PERIPARTURIENT DAIRY COWS WHICH WILL MINIMIZE BODY WEIGHT LOSS AND MAXIMIZE LACTATION PERFORMANCE. WE WILL USE IN VITRO AND IN VIVO STUDIES TO TEST OUR HYPOTHESIS.WE WILL DETERMINE HOW OLEIC ACID EXERTS LIPOGENIC AND INSULIN SENSITIZING EFFECTS IN ADIPOSE TISSUE AND HOW DIETARY SUPPLEMENTATION OF OLEIC ACID EFFECTS MILK PRODUCTION AND BODY WEIGHT LOSS ACROSS THE PERIPARTURIENT PERIOD.COLLECTIVELY, THESE OUTCOMES WILL ENABLE US TO POSITIVELY IMPACT DAIRY CATTLE PERFORMANCE, PRODUCTION EFFICIENCY, AND FARM INCOME BY GAINING INSIGHT ON STRATEGIES TO INCREASE NUTRIENT USE FOR MILK SYNTHESIS.OUR ORIGINAL RESEARCH FINDINGS WILL TRANSLATE INTO IMMEDIATE APPLICATION ON US DAIRY FARMS, AND THUS ADVANCE THE COMPETITIVENESS AND SUSTAINABILITY OF THE DAIRY INDUSTRY.