**AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** EARLY EMBRYONIC MORTALITY REMAINS AS A MAJOR SOURCE OF ECONOMIC LOSS FOR THE DAIRY INDUSTRY. CHROMOSOME ABNORMALITIES ARE THE SINGLE MOST COMMON CAUSE OF CONGENITAL BIRTH DEFECTS AND PREGNANCY LOSS IN MAMMALS. YET, THE CAUSES AND MECHANISMS OF CHROMOSOME INSTABILITY ARE NOT KNOWN. HERE, WE USE STATE OF THE ART GENOMICS AND HIGH-RESOLUTION METHODS TO DISSECT THE MECHANISMS LEADING TO CHROMOSOME INSTABILITY IN BOVINE OOCYTES AND EMBRYOS. OUR STUDIES HAVE IMPORTANT IMPLICATIONS FOR THE IDENTIFICATION OF NOVEL EPIGENETIC MARKERS OF OOCYTE QUALITY AND DEVELOPMENTAL POTENTIAL REQUIRED FOR FEMALE FERTILITY AND TO IMPROVE BOVINE REPRODUCTIVE EFFICIENCY.