** AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** NO DAIRY COW IN THE UNITED STATES CAN AVOID HEAT STRESS. TO DEVELOP TARGETED HEAT ABATEMENTSTRATEGIES THAT JUDICIOUSLY USE RESOURCES AND PROMOTE DAIRY COW WELFARE, WE MUST FIRST UNDERSTANDTHE BEHAVIORAL VARIABILITY OF THE HEAT STRESS RESPONSE AND PHENOTYPICALLY CHARACTERIZE A SUITE OF NONINVASIVEMETRICS THAT ARE REPRESENTATIVE OF AN INDIVIDUAL COW THAT CAN REMAIN CONSISTENTLYPRODUCTIVE DURING THERMALLY CHALLENGING ENVIRONMENTS. WE SEEK TO NON-INVASIVELY CHARACTERIZE 1)THE BEHAVIORAL AND PHYSIOLOGICAL VARIABILITY OF THE HEAT STRESS RESPONSE, 2) THE INTERACTION BETWEENTEMPERAMENT AND THERMOTOLERANCE, AND 3) THE GENOTYPES OF COWS THAT DIFFER IN THEIR ABILITY TO COPEWITH HEAT STRESS. A SUITE OF INDIVIDUAL COW RESPONSES WILL BE COLLECTED DURING MULTIPLEENVIRONMENTAL CONDITIONS USING A VARIETY OF DISPARATE DATA COLLECTION STRATEGIES. DURING LACTATION,COWS WILL BE MONITORED USING BODY-MOUNTED SENSORS (E.G., STANDING, LYING, RUMINATION), AUTOMATICROBOTIC MILKING SYSTEMS (E.G., ROBOT BEHAVIOR,MILK LET-DOWN REFLEX), VIDEO ANALYTICS (E.G., WATERUSE, BRUSH USE), PRODUCTIVITY (E.G., MILK FAT, MILK YIELD, SSC), REPRODUCTIVE SUCCESS (E.G., DIM ATFIRST SERVICE), AND HEALTH EVENTS (E.G., ACIDOSIS, LAMENESS, MASTITIS). DURING THE DRY PERIOD, COWTEMPERAMENT WILL BE EVALUATED USING A STARTLE TEST. THESE RESULTS WILL BE COMBINED WITH GENOTYPEAND USED TO CHARACTERIZE KNOWN AND NOVEL PHENOTYPES, AND EVALUATE THE ASSOCIATIONS AND VARIABILITYOBSERVED THEREIN. THE KNOWLEDGE GAINED FROM THIS PROPOSAL IS EXPECTED TO IDENTIFY A NOVELTEMPERAMENT SELECTION STRATEGY FOR DAIRY COWS REGARDING THERMOTOLERANCE AND IDENTIFY A SUITE OFNON-INVASIVE ANIMAL-BASED METRICS INDICATIVE OF THERMOTOLERANCE THAT CAN BE INTEGRATED INTO GENETICSELECTION DECISIONS.