**AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** PREGNANCY FAILURES ARE PRONOUNCED DURING THE FIRST MONTH OF GESTATION IN LACTATING DAIRY AND SUCKLING BEEF CATTLE. ONLY 30-50% OF LACTATING DAIRY COWS AND 45-55% OF BEEF COWS WILL PRODUCE A LIVE CALF AFTER EACH MATING. BETWEEN 80 AND 95% OF THESE FAILED PREGNANCIES OCCUR DURING THE FIRST MONTH OF GESTATION. A BETTER UNDERSTANDING OF THE FUNDAMENTAL EVENTS THAT CONTROL THE NORMAL PROGRESSION OF PREGNANCY DURING THE FIRST MONTH OF GESTATION WILL PROVIDE OPPORTUNITIES TO DIAGNOSE PROBLEMS AND MANIPULATE PHYSIOLOGICAL SYSTEMS IN WAYS THAT IMPROVE PREGNANCY RETENTION. THE LONG-TERM, OVERARCHING GOALS OF THIS PROJECT ARE TO 1) EXAMINE THE CELLULAR MECHANISMS THAT INFLUENCE EMBRYO DEVELOPMENT DURING THE FIRST MONTH OF GESTATION, AND 2) TRANSLATE THIS FUNDAMENTAL KNOWLEDGE OF EMBRYO DEVELOPMENT BY DEVELOPING REPRODUCTIVE TECHNOLOGIES AND MANAGEMENT STRATEGIES THAT WILL REDUCE THE INCIDENCE OF PREGNANCY FAILURES IN DAIRY AND BEEF CATTLE. THE OBJECTIVES OF THIS PROJECT ARE TO EXPLORE THE ABILITY OF INTERLEUKIN-6, AND COMPOUND PRODUCED BY THE UTERUS AND EMBRYO DURING EARLY PREGNANCY, TO CONTROL EMBRYO DEVELOPMENT IN CATTLE AND TO IMPROVE SURVIVAL OF PREGNANCIES AFTER EMBRYO TRANSFER. THE ANTICIPATION IS THAT NEW FEATURES OF EMBRYO DEVELOPMENT WILL BE DESCRIBED IN THIS WORK AND THAT INTERLEUKIN-6 SUPPLEMENTATION BEFORE EMBRYO TRANSFER WILL IMPROVE PREGNANCY RATES AND CALF HEALTH AFTER BIRTH. THIS WORK WILL FILL CRITICAL GAPS IN SCIENTIFIC KNOWLEDGE AND HAS THE POTENTIAL TO OFFER DAIRY AND BEEF COW PRODUCERS WITH NEW TOOLS FOR LIMITING PREGNANCY FAILURES DURING THE FIRST MONTH OF GESTATION.