BOVINE RESPIRATORY DISEASE (BRD) IS THE LEADING CAUSE OF DISEASE IN BEEF CATTLE ACROSS NORTH AMERICA AND THEREFORE, BRD IS ONE OF THE MAIN ECONOMIC AND WELFARE CONCERNS IN BEEF CATTLE PRODUCTION. BRD IS ALSO THE LEADING CAUSE OF ANTIMICROBIAL USE IN BEEF CATTLE; THUS, DISCOVERIES THAT DECREASE BRD WILL ALSO DECREASE ANTIMICROBIAL USE AND DECREASE ANTIMICROBIAL RESISTANCE. THE DIAGNOSIS AND TREATMENT OF BRD IS OFTEN MADE FROM CLINICAL SIGNS, BUT THIS MISSES ANIMALS WITH SUBCLINICAL DISEASE. THIS FREQUENTLY LEADS TO MISDIAGNOSING ANIMALS THAT HAVE SUBCLINICAL BRD AS HEALTHY. IF VETERINARIANS AND CATTLE PRODUCERS COULD ACCURATELY PREDICT WHICH CATTLE ARE LIKELY TO DEVELOP OR RESIST BRD BEFORE IT OCCURS, THEY COULD FOCUS ATTENTION ON THE CATTLE LIKELY TO DEVELOP DISEASE, WHICH SHOULD IMPROVE ACCURACY AND EFFICIENCY OF DETECTION AND TREATMENT. OUR HYPOTHESIS IS THAT BEEF CATTLE THAT REMAIN HEALTHY CAN BE IDENTIFIED, AT FEEDING FACILITY ARRIVAL, TO HAVE INCREASED LEVELS OF ACTIVITY OF SPECIFIC GENES INVOLVED IN PROCESSES FOR BRD RESISTANCE. WE WILL FOCUS ON TWO MAIN OBJECTIVES WITH THIS PROJECT. FIRST, USING BLOOD TESTING, WE WILL COMPARE THE ACTIVITY OF GENES IN CATTLE THAT NEVER DEVELOP BRD VERSUS THOSE THAT DEVELOP BRD WITHIN 28 DAYS OF THEIR ARRIVAL. SECOND, WE WILL DEVELOP A MORE RAPID AND SIMPLE TEST TO IDENTIFY THE GENES THAT WE LEARNED ARE DIFFERENT IN CATTLE THAT DEVELOP BRD VERSUS CATTLE THAT REMAIN HEALTHY. WE ARE EXPECTING TO FIND GENES AT ARRIVAL THAT ACCURATELY PREDICT WHETHER CATTLE DEVELOP BRD OR REMAIN HEALTHY OVER TIME. THIS WORK WILL LEAD TO A BETTER UNDERSTANDING OF WHY CATTLE DEVELOP OR RESIST BRD, AND WILL CREATE TOOLS THAT WILL HELP SCIENTISTS, VETERINARIANS, AND CATTLE PRODUCERS DETERMINE CATTLE THAT ARE LIKELY TO STAY HEALTHY OR DEVELOP BRD, SUPPORTING THE DEVELOPMENT OF BETTER PROTOCOLS TO IDENTIFY, TREAT, AND PREVENT BRD IN CATTLE.