** AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** POULTRY IS THE THIRD-LARGEST AGRICULTURAL COMMODITY. EGGS AND POULTRY MEAT CONSTITUTE THE CHIEF PROTEIN COMPONENT OF THE AMERICAN DIET AND REPRESENT THE PRINCIPAL SOURCE OF PROTEIN WORLDWIDE. WITH THE RAPID GROWTH OF THE WORLD POPULATION, INCREASED GLOBAL DEMAND FOR HIGH-QUALITY POULTRY PRODUCTS WARRANTS INNOVATIVE WAYS TO IMPROVE CHICKEN REPRODUCTIVE EFFICIENCY. BESIDES COMMON REPRODUCTIVE DISEASES IN THE OVARY AND OVIDUCT, FLOCK FERTILITY AND REDUCED SPERM PRODUCTION ARE COMMON CONCERNS IN POULTRY PRODUCTION. CHICKEN PRIMORDIAL GERM CELLS (PGCS) ARE THE UNIPOTENT PRECURSORS OF SPERM CELLS AND OVA, ESSENTIAL FOR FLOCK FERTILITY. PGCS PASS GENETIC MATERIAL FROM ONE GENERATION TO THE NEXT. THEREFORE, A DEEPER UNDERSTANDING OF THE FORMATION AND DIFFERENTIATION OF PGCS IS CRITICAL TO ADVANCE APPROACHES TO IMPROVE THE REPRODUCTION EFFICIENCY OF POULTRY. SPECIFICALLY, THE DIFFERENTIATION MECHANISMS OF CHICKEN EMBRYONIC STEM CELLS (ESCS) INTO PRIMORDIAL GERM CELLS (PGCS) AND PGCS INTO SPERMATOGONIAL STEM CELLS (SSCS) ARE CRITICAL FOR SPERM PRODUCTION IN CHICKENS. THE PRIMARY BREEDING COMPANIES MAINTAIN PEDIGREED LINES UNDER CONSTANT SELECTION FOR PRODUCTION TRAITS WITHIN THE LAYER, BROILER, AND TURKEY INDUSTRIES.THE MAIN GOAL OF BROILER CHICKEN REPRODUCTION IS TO PRODUCE HIGH-QUALITY FERTILIZED EGGS. FLOCK FERTILITY IS THE MOST SIGNIFICANT REPRODUCTIVE ISSUE THE BROILER INDUSTRY CURRENTLY FACES. THE PERCENTAGE OF FERTILE EGGS PRODUCED DEPENDS ON OVULATION AND SEMEN PRODUCTION LEVELS. THE TRAIT IS OF CONSIDERABLE INTEREST IN THE BROILER INDUSTRY AND IS AN ISSUE FOR MALES MORE THAN FEMALES PRIMARILY BECAUSE OF THE EFFECT OF SEMEN QUALITY ON CHICK OUTPUT. THERE IS A NEGATIVE CORRELATION BETWEEN GROWTH AND FERTILITY; THUS, THE BROILER AND TURKEY INDUSTRIES MAINLY PERFORM LABOR-INTENSIVE ARTIFICIAL INSEMINATION. THEREFORE, OPPORTUNITIES EXIST TO IMPROVE FERTILITY IN BROILER STOCKS. BEINGUNIPOTENT PRECURSORS OF SPERM CELLS AND OVA, CHICKEN ESCS, AND PGCS ARE CRITICAL FOR DETERMINING FERTILIZED EGG RATE AND FLOCK FERTILITY AND, IMPORTANTLY, TRANSMIT GENETIC INFORMATION TO FUTURE GENERATIONS. ALTHOUGH A DYNAMIC SELECTION OF THE EARLY GERM CELL POPULATIONS IS AN ESSENTIAL BIOLOGICAL FEATURE LINKED TO FERTILITY, THEIR HETEROGENEITY AND HALLMARKS IN AVIAN SPECIES HAVE NOT BEEN FULLY CHARACTERIZED. WE STILL DO NOT KNOW THE REGULATORY MECHANISMS OF FORMATION, DEVELOPMENT, AND DIFFERENTIATION AND ARE FACED WITH A LIMITED NUMBER OF PGCS PER EMBRYO. THUS, WE HYPOTHESIZE THAT REGULATORY ELEMENTS EPIGENETICALLY CONTROL THE FATES OF GERM CELL LINEAGES IN CHICKEN EMBRYONIC STEM CELLS. ASCERTAINING THESE REGULATORY ELEMENTS IS ESSENTIAL TO MODULATE THE TRANSITION FROM QUIESCENCE TO PROLIFERATION AND DIFFERENTIATION IN CHICKEN ESCS AND PGCS. SPECIFICALLY, CHARACTERIZING THE REGULATORY MECHANISMS WILL PROVIDE DEEP INSIGHTS INTO CHICKEN STEM CELL BIOLOGY, UNCOVERING BIOMARKERS OF PGCS THAT ARE MORE LIKELY OR ABLE TO DIFFERENTIATE, PARTICULARLY IN THE BROILER BREEDER INDUSTRY.,IT IS POSSIBLE TO DEVELOP AN EPIGENETIC STRATEGY FOR THE SEX CONTROL OR IDENTIFICATION OF EARLY EMBRYOS, I.E., NOT LIKE GENOMIC MODIFICATION (GM) METHODS, INCREASING THE ECONOMIC BENEFITS OF POULTRY PRODUCTION AS THE BROILER INDUSTRY PREFERS MORE MALE CHICKS, AND VICE VERSA FOR LAYERS. BESIDES PROVIDING NEW KNOWLEDGE OF CHICKEN GERM CELL DEVELOPMENTAL TRANSITIONS AND PLASTICITY, THE PROJECT'S RESULTS WILL SIGNIFICANTLY HELP US UNDERSTAND CHICKEN EMBRYONIC STEM CELL BIOLOGY, IMPROVING THE EFFICIENCY OF INDUCING SOMATIC CELLS TO BECOME PGCS AND RESULTING IN SIGNIFICANT INTEREST AMONG POULTRY SCIENCE AND PRODUCERS.