** AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** WHEN DAIRY COWS GIVE BIRTH AND BEGIN LACTATING, THERE IS A TREMENDOUS DRAW OF CALCIUM FROM THE BODY FOR PRODUCTION OF MILK. ALTHOUGH AT TIMES THIS CALCIUM EXPENDITURE IS SO SEVERE THAT IT RENDERS COWS UNABLE TO STAND, THIS CLINICAL FORM OF DISEASE IS FORTUNATELY UNCOMMON. HOWEVER, APPROXIMATELY 50% OF COWS EXHIBIT A MILD FORM OF LOW BLOOD CALCIUM, CALLED HYPOCALCEMIA, AND MILDHYPOCALCEMIA CAN INCREASE THE RISK OF OTHER DISEASES AND NEGATIVELY IMPACT MILK PRODUCTION. HOWEVER, WE HAVE PRELIMINARY EVIDENCE THAT NOT ALL EARLY LACTATION MILDHYPOCALCEMIAIS DETRIMENTAL, AND WE AIM TO CRITICALLY ASSESS THIS LONG-STANDING BELIEF. WE HYPOTHESIZE THAT EARLY LACTATION COWS WITH GOOD FOOD INTAKE AND APPROPRIATE MAMMARY GLAND FUNCTION WILL ONLY EXPERIENCE A SHORT PERIOD OF HYPOCALCEMIA AND GO ON TO PRODUCE HIGH VOLUMES OF MILK. IN CONTRAST, COWS THAT DO NOT EAT WELL AFTER CALVING AND EXPERIENCE ALTERED MAMMARY GLAND FUNCTION, CHRONIC INFLAMMATION, AND ACTIVATION OF THEIR IMMUNE SYSTEMS WILL UNDERGOLONGER PERIODS OF HYPOCALCEMIA RESULTING IN REDUCED MILK PRODUCTION. OUR OBJECTIVES ARE TO UNDERSTAND HOW INTAKE OF FOOD, INFLAMMATION RESULTING FROM CALVING, AND IMMUNE SYSTEM ACTIVATION AFFECT CALCIUM REGULATION AND MILK PRODUCTION AND TO IDENTIFY HOW A COW'S MAMMARY GLAND SUPPORTS THIS INTERACTION. WE EXPECT TO IDENTIFY DIFFERENCES IN THE SEQUENCE OF EVENTS AROUND CALVING THAT LEAD TO DEVELOPMENT OF SHORT VERSUS LONG-TERM MILD HYPOCALCEMIA AND DETERMINE HOW THE MAMMARY GLAND IMPACTS THESE EVENTS. OUR RESULTS WILL PROVIDE PRODUCERS WITH DIRECT AND IMMEDIATE KNOWLEDGE OF WHICH COWS REQUIRE ATTENTION TO MAINTAIN THEIR CALCIUM STATUS, WHEN THAT ATTENTION NEEDS TO BE GIVEN, AND WHAT METHODS WE CAN APPLY TO IMPROVE COW HEALTH AND MILK PRODUCTION.