** AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** ANTIMICROBIAL USE (AMU) IN FOOD ANIMALS IS A CONTRIBUTOR TO ANTIMICROBIAL RESISTANCE (AMR) GLOBALLY. THE EFFECTS OF AMU REDUCTION IN ANIMAL PRODUCTION AND WELFARE, FOOD SAFETY, AND ENVIRONMENTAL AMR MITIGATION ARE POORLY UNDERSTOOD. THE OBJECTIVE OF THIS PROPOSAL IS TO DETERMINE THE IMPACT OF AMU ON MICROBIAL DIVERSITY, PREVALENCE OF AMR GENES, AND GENES INVOLVED IN HORIZONTAL GENE TRANSFER IN ENVIRONMENTAL SAMPLES FROM ANTIMICROBIAL-FREE AND CONVENTIONAL (I.E., FARMS THAT USE ANTIMICROBIALS AS PROPHYLACTICS) FARMS. WE WILL ALSO COMPARE BIRD MORBIDITY AND MORTALITY BETWEEN THESE TWO CATEGORIES AND IDENTIFY FACTORS THAT CONTRIBUTE TO HEALTH AND DISEASE PREVENTION. THIS INFORMATION WILL BE USED TO INFORM PRODUCERS OF IMPORTANT FACTORS CONTRIBUTING TO AMR AND HOW TO CONTROL IT. IT WILL ALSO INFORM THE SOURCES OF AMR TRANSMISSION FROM OUTSIDE TO INSIDE POULTRY HOUSES AND HOW TO IMPROVE BIOSECURITY TO AVOID THESE EVENTS. OUR SPECIFIC OBJECTIVES ARE TO (1) IDENTIFY POPULATION DIVERSITY AND PREVALENCE OF AMR GENES IN ENVIRONMENTAL SAMPLES FROM BROILER, BREEDER, AND PULLET FARMS AND HATCHERIES USING METAGENOMIC APPROACHES; (2) IDENTIFY TRANSMISSION PATHWAYS OF AMR GENES BETWEEN SAMPLE TYPES AND LOCATION INSIDE AND OUTSIDE THE POULTRY HOUSE AND BETWEEN HOUSES; (3) IDENTIFY THE IMPACT OF AMU AND FARM PRACTICES ON MICROBIOME CONNECTIONS AND TRANSMISSION OF AMR GENES. THIS RESEARCH WILL INFORM BEST PRACTICES TO REDUCE AMU WITHOUT COMPROMISING ANIMAL HEALTH AND PRODUCTIVITY. MITIGATING AMR IN POULTRY FARMS WILL IMPROVE FOOD SAFETY IN THE USA BY AVOIDING FARM-TO-FORK TRANSMISSION OF AMR PATHOGENS AND IMPROVING FOOD PRODUCTION EFFICIENCY BY REDUCING RECALLS.