ANIMAL HEALTH IS ESSENTIAL TO THE GROWTH AND SUSTAINABILITY OF THE FOOD SYSTEM. IN ORDER TO CONTINUE TO PROVIDE A HIGH-QUALITY PRODUCT TO CONSUMERS, IMPROVING ANIMAL HEALTH IN THE FACE OF DISEASE IS CRITICAL. BOVINE VIRAL DIARRHEA VIRUS (BVDV) IS A DISEASE THAT CAN BE COMPLEXED WITH OTHER RESPIRATORY PATHOGENS THROUGHOUT THE LIFESPAN OF CATTLE. BEEF AND DAIRY CATTLE REPRESENT ONE OF THE LARGEST SECTORS OF THE ECONOMY, INCLUDING MILLIONS OF JOBS FROM RANCHERS TO VETERINARIANS, ENSURING THE HEALTH AND WELLBEING OF THESE ANIMALS IS PARAMOUNT. VACCINATIONS AGAINST THESE PATHOGENS ARE DELIVERED IN SEVERAL FORMS: A MODIFIED-LIVE VACCINATION (MLV) CONTAINS A STRAIN OF THE VIRUS THAT HAS BEEN ATTENUATED, OR ALTERED, IN SOME WAY TO REPLICATE IN THE BODY, BUT WILL NOT CAUSE THE ANIMAL TO EXPERIENCE THE DISEASE. THIS VACCINATION TYPE POTENTIALLY ALLOWS THE IMMUNE SYSTEM TO RECOGNIZE A PATHOGEN MORE READILY, AS IT ALREADY HAD TO DEVELOP ANTIBODIES TO THE VIRUS IN THE VACCINE. ANOTHER TYPE OF VACCINATION IS THE USE OF A KILLED VIRAL VACCINATION (KV), WHICH CONTAINS THE VIRUS THAT HAS BEEN COMPLETELY INACTIVATED. THE KV VACCINATION IS OFTEN USED MORE READILY IN PRODUCTION SYSTEMS AS IT POSES LITTLE THREAT TO THE ANIMAL TO REGAIN VIRULENCE OR QUALITIES THAT CAN MAKE THE ANIMAL SICK. WHILE VACCINATIONS AGAINST THESE PATHOGENS HAVE BEEN ON THE MARKET FOR DECADES, WE STILL SEE AN INCIDENCE OF THESE DISEASES AT DIFFERENT STAGES OF CATTLE PRODUCTION. THESE DISEASES CAN RESULT IN MILLIONS OF DOLLARS IN LOSSES THROUGHOUT THE COMBINATION OF TREATMENT COSTS, LABOR COSTS, AND REDUCED GROWTH, AND INCREASED COSTS TO CONSUMERS. THUS, THIS PROPOSAL IS AIMED AT EXAMINING HOW THE USE OF DIFFERENT VACCINATION TREATMENTS WHILE A COW IS PREGNANT WITH HER CALF, CAN AFFECT THE CALF'S PERFORMANCE WHEN THEY ARE DIRECTLY EXPOSED TO THESE PATHOGENS. SPECIFICALLY, WE ARE TESTING THE EFFICACY OF A MLV COMPARED TO A KV VACCINATION ON CATTLE GRAZING NATIVE RANGELAND THROUGH THEIR CALVES. UPON CALVING, BOTH THE COW AND HER CALF WILL BE SAMPLED FOR BLOOD TITERS AGAINST BVDV. COLOSTRUM, THE FIRST MILK FROM THE COW, WILL BE COLLECTED AS WELL TO ANALYZE TITERS AGAINST BVDV. AFTER INITIAL DAY 1 SAMPLING, RUMINAL CONTENTS, AND BLOOD WILL BE COLLECTED FROM BOTH COW AND CALF, AS WELL AS MILK FROM THE COW TO EXAMINE THE CHANGES IN THE RUMEN MICROBIOME AND METABOLOME AS THE CALF AGES AND DEVELOPS A FULLY FUNCTIONAL RUMEN. AFTER CALVES ARE WEANED, THEY WILL UNDERGO A FEED EFFICIENCY STUDY WHERE EACH CALF'S INDIVIDUAL FEED INTAKE AD GAIN WILL BE MEASURED FOR 60 DAYS. IMPROVING FEED EFFICIENCY IS A CRITICAL PART OF BEEF PRODUCTION SYSTEMS, TO REQUIRE LESS INPUT FOR GREATER OUTPUT. AFTER COLLECTING INDIVIDUAL FEED INTAKE DATA, CALVES WILL BE IMMUNE CHALLENGED THROUGH EXPOSURE TO BVDV, AND RESPONSE VARIABLES WILL BE MEASURED, INCLUDING BEHAVIORAL CHANGES, WEIGHT LOSS OR GAIN, BLOOD MEASUREMENTS OF WHITE BLOOD CELLS, AND ISOLATION OF THE VIRUS. ULTIMATELY, THROUGH THESE METHODS, WE AIM TO ANSWER QUESTIONS OF IMPROVED IMMUNITY, FEED EFFICIENCY, AND GROWTH OF CALVES THROUGH DIFFERENT VACCINATION STRATEGIES FROM THEIR DAM. IF THIS GOAL IS MET, WE HOPE TO PROVIDE IMPROVED RECOMMENDATIONS TO COW/CALF PRODUCERS, VETERINARIANS, AND ANIMAL HEALTH COMPANIES ABOUT THE BEST HERD HEALTH PROGRAM FOR THEIR CATTLE WHICH MANIFESTS IN BETTER PROTECTION AGAINST DISEASES.