DAIRY COWS (CATTLE THAT HAVE HAD AT LEAST ONE CALF) ARE VERY DIFFICULT TO GET PREGNANT AGAIN. IF COWS DON'T GET PREGNANT AND ARE UNABLE TOHAVE ANOTHER CALF THEY CANNOT PRODUCE MILK AGAIN. MANY COWS GET PREGNANT BUT THEN LOSE THE CALF DUE TO PREGNANCY LOSS.THIS PROJECT IS DESIGNED TO GAIN A GREATER UNDERSTANDING WHY COWS LOSE PREGNANCIES AND TEST WAYS TO ENSURE THAT WHEN COWS DO GET PREGNANT THEY CAN MAINTAIN THE PREGNANCY THROUGHOUT A FULL GESTATION. FINDING WAYS TO AVOID EARLY PREGNANCY LOSS CAN HAVE A DRAMATIC IMPACT ON THE PROFITABILITY OF DAIRY FARMS.HEIFERS (CATTLE THAT HAVE NOT YET HAD A CALF) ARE HIGHLY FERTILE AND MAKE AN EXCELLENT MODEL TO DETERMINE WHY DAIRY COWS HAVE SUCH HIGH PREGNANCY LOSSES. WE FOUNDTHAT THE EMBRYO OF A HEIFER IMPLANTS INTO THE UTERUS AT A VERY SPECIFIC TIME COMPARED TO COWS THAT IMPLANT MUCH LATER AND OVER A LONGER PERIOD. THIS PROPOSAL WILL GAIN NEW KNOWLEDGE AS TO WHY THIS HAPPENS AND IF TREATMENT WITH A FERTILITY PROGRAM EARLY IN THE PREGNANCY OF COWS WILL ALLIEVIATE THE PROBLEM OF PREGNANCY LOSS. WE HYPOTHESIZE THAT THESE FERTILITY PROGRAMS WILL INCREASE THE COW'S PRODUCTION OF THE HORMONE PROGESTERONE DURING THE EARLY GROWTH OF THE EMBRYO AND THIS WILL CAUSE THE COW'S EMBRYO TO IMPLANT SOONER AND MAINTAIN A FULL PREGANCY. WE HAVE DESIGNED THREE STUDIES USING BOTH HEIFERS AND COWS TO DETERMINE THE IMPACT OF INCREASING THE COW'S PROGESTERONE ON PREGNANCY.