**AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** SALMONELLA DUBLIN IS AN IMPORTANT PATHOGEN AMONG DAIRY CATTLE, CAUSING SEVERE DISEASE OUTBREAKS AND DEATHS, AND IT ALSO POSES A CONSIDERABLE THREAT TO HUMAN HEALTH. CONTROL OF THIS DISEASE IS UNIQUELY CHALLENGING BECAUSE INFECTED CATTLE CAN BECOME CARRIERS, SHEDDING SALMONELLA DUBLIN IN FECES AND MILK ON A LONG-TERM BASIS. HOWEVER, THERE ARE SIGNIFICANT GAPS IN OUR UNDERSTANDING OF HOW THIS PATHOGEN IS SPREAD AND HOW BEST TO CONTROL IT. OUR OVERALL GOAL IS TO USE NOVEL TESTING METHODS AND SAMPLE TYPES TO CHARACTERIZE SALMONELLA DUBLIN TRANSMISSION IN DAIRY CATTLE, THUS ENABLING THE DEVELOPMENT OF SUCCESSFUL DISEASE MANAGEMENT STRATEGIES. THIS WILL BE ACHIEVED THROUGH FOUR SPECIFIC OBJECTIVES: (1) DETERMINE THE PATTERNS OF SALMONELLA DUBLIN SHEDDING AMONG CALVES WITH CONFIRMED CLINICAL DISEASE, USING NASAL SWAB, SALIVA, AND FECAL SAMPLES; (2) ESTIMATE THE DURATION OF SHEDDING IN INFECTED CALVES AND IDENTIFY FACTORS THAT INCREASE THE RISK OF BECOMING A CARRIER; (3) IDENTIFY SOURCES OF SALMONELLA DUBLIN TRANSMISSION TO CALVES THROUGH TESTING OF ENVIRONMENTAL LOCATIONS AND ADULT COWS; (4) DETERMINE THE ROLE OF OFF-SITE HEIFER RAISING IN SPREADING SALMONELLA DUBLIN. EXPECTED RESULTS INCLUDE A COMPREHENSIVE UNDERSTANDING OF SALMONELLA DUBLIN SHEDDING PATTERNS AMONG DAIRY CALVES, IDENTIFICATION OF SPECIFIC FACTORS THAT INCREASE THE RISK OF LONG-TERM CARRIER STATUS, AND RECOGNITION OF PRACTICES THAT PROMOTE INTRODUCTION OF SALMONELLA DUBLIN INTO DAIRY HERDS AND SUBSEQUENT TRANSMISSION WITHIN HERDS. THE ANTICIPATED IMPACT OF THIS PROJECT IS IMPROVED CONTROL OF DISEASE CAUSED BY SALMONELLA DUBLIN IN DAIRY CATTLE, THROUGH (1) NEW DIAGNOSTIC PROTOCOLS THAT ENABLE RAPID DETECTION IN READILY ACCESSIBLE CLINICAL SAMPLES AND (2) EVIDENCE-BASED MANAGEMENT STRATEGIES TO REDUCE THE SPREAD OF THIS DISEASE WITHIN AND AMONG DAIRY FARMS.