** AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** THE UTILIZATION OF LABORATORY-DERIVED, OR IN VITRO PRODUCED (IVP) EMBRYOS, HAS BECOME VITAL TO THE BEEF AND DAIRY CATTLE INDUSTRIES. IVP EMBRYOS ALLOW FOR PROPAGATION OF GENETIC TRAITS FROM ELITE ANIMALS AND INCREASE THE EFFICIENCY OF CATTLE PRODUCTION SYSTEMS, THEREBY CONTRIBUTING TO A MORE SUSTAINABLE AND SECURE FOOD SOURCE FOR A CONTINUALLY INCREASING GLOBAL POPULATION. HOWEVER, IVP EMBRYOS HAVE SEVERAL ROADBLOCKS TO SUCCESSFUL DEVELOPMENT AND ESTABLISHMENT OF PREGNANCY. WHEN THE FEMALE GAMETE, OR OOCYTE, IS REMOVED FROM THE OVARY, IT ENCOUNTERS SEVERAL STRESSORS THAT CAN SIGNIFICANTLY REDUCE ITS QUALITY. IN FACT, LESS THAN 40% OF OOCYTES GO ON TO PRODUCE A VIABLE EMBRYO FOR TRANSFER. THEREFORE, IT IS CRITICAL TO ADDRESS OOCYTE-SPECIFIC FACTORS THAT CONTRIBUTE TO POOR DEVELOPMENT OF IVP EMBRYOS. THE OVERALL GOAL OF THIS RESEARCH PROPOSAL IS TO UNDERSTAND HOW STRESS FACTORS, NAMELY OXIDATIVE STRESS DURING CULTURE, LEADS TO POOR MATURATION AND DEVELOPMENTAL COMPETENCE OF THE OOCYTE. TO ACCOMPLISH THIS, WE WILL PERFORM CULTURE OF OOCYTES UNDER DIFFERENT CONDITIONS TO DETERMINE HOW OXIDATIVE STRESS IMPACTS THE WAY GENES ARE REGULATED WITHIN THE OOCYTE. CERTAIN MARKS, OR METHYLATION, ON GENES DETERMINE THEIR ABILITY TO BE EITHER DEGRADED OR MADE INTO PROTEIN FOR A CERTAIN FUNCTION. SPECIFICALLY, IT IS OUR GOAL TO DETERMINE HOW DEPOSITION OR REMOVAL OF THESE METHYLATION MARKS MAY BE IMPACTED BY METABOLIC CHANGES IN THE OOCYTE DUE TO EXTERNAL STRESSORS. WE EXPECT THAT OXIDATIVE STRESS CAUSED BY LABORATORY CULTURE OF OOCYTES ALTERS THE PROTEINS THAT CONTROL THESE METHYLATION MARKS, THUS ALTERING THE REGULATION OF GENES. ULTIMATELY, OUR WORK TO UNCOVER THESE MECHANISMS MAY LEAD TO NEW EMBRYO CULTURE TREATMENTS THAT WILL ALLOW FOR A GREATER NUMBER OF HIGH-QUALITY EMBRYOS PRODUCED FOR BEEF AND DAIRY CATTLE PRODUCTION SYSTEMS.