**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 PREGNANCY LOSS IS A COMMON ISSUE AFFECTING FERTILITY OF BEEF COWS AND REDUCING PROFITABILITY OF BEEF PRODUCERS. PREGNANCY LOSS CAN BE RELATED TO UNDERNUTRITION AND BODY WEIGHT LOSS DURING EARLY PREGNANCY. WE IDENTIFIED BREEDS OF CATTLE THAT ARE MORE RESILIENT TO UNDERNUTRITION AND EXPERICELESSPREGNANCY LOSSIN COMPARISON TO THE MOST COMMON BEEF BREEDS IN THE U.S. OUR HYPOTHESIS IS THAT GENETIC AND METABOLIC DIFFERENCES EXIST BETWEEN BREEDS OF CATTLE THAT ALLOW FOR AN INCREASED RESILIENCE TO UNDERNUTRITION AND DECREASED PREGNANCY LOSS. THE OBJECTIVE OF THIS PROJECT IS TO CHARACTERIZE DIFFERENCES IN EARLY EMBRYONIC DEVELOPMENT AND UTERINE ENVIRONMENT BETWEEN BREEDS OF CATTLE THAT ARE MORE RESILIENT AND CAN BETTER MAINTAIN PREGNANCY ANDBREEDS OF CATTLE THAT SUFFER MORE PREGNANCY LOSS WHEN EXPOSED TO UNDERNUTRITION. UNDERSTANDING THOSE DIFFERENCES WILL ALLOW THE DEVELOPMENT OF STRATEGIES TO INCORPORATE SPECIFIC GENOTYPES FROM MORE RESILIENT BREEDS OF CATTLE TO REDUCE PREGNANCY LOSS AND HELP ENHANCE SUSTAINABILITY AND PROFITABILITY OF AMERICAN BEEF PRODUCTION.