** AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** AFTER HATCHING, COMMERCIALLY REARED CHICKENS ARE MAINLY EXPOSED TO ENVIRONMENTAL BACTERIA, INCLUDING ENTEROBACTERIACEAE, THAT NEGATIVELY AFFECT ANIMAL HEALTH AND PRODUCTIVITY AND ARE OF FOOD SAFETY CONCERN. HOWEVER, EARLY EXPOSURE TO SOME KEY GUT BACTERIA, LIKE SEGMENTED FILAMENTOUS BACTERIA (SFB), COULD HELP SHAPE A HEALTHY GUT, WHICH IN TURN CAN IMPROVE OVERALL HEALTH. WE PROPOSE TO EVALUATE HOW SFB DRIVE CHICKEN GUT MATURATION AND PREVENT COLONIZATION OF SOME BACTERIA, SUCH AS SALMONELLA, IN CHICKENS. OUR SPECIFIC OBJECTIVES ARE TO 1) DEVELOP AN SFB-INOCULUM FOR THE TREATMENT OF CHICKENS; 2) EVALUATE HOW SFB TREATMENT INCREASES GUT MATURATION AND IMMUNE STIMULATION; AND 3) TEST THE RESISTANCE AGAINST INTESTINAL ENTEROBACTERIACEAE, E.G., SALMONELLA ENTERICA SPECIES IN CHICKENS. OVERALL, WE EXPECT THE PROPOSED TREATMENT WILL IMPROVE GUT MATURATION IN EARLY LIFE, WHICH WILL INCREASE POULTRY HEALTH AND PRODUCTIVITY.