Project Grant 20226800836355

**AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** THE COW-CALF INDUSTRY SPENDS MILLIONS OF DOLLARS A YEAR TO VACCINATE COWS AGAINST VIRUSES THAT CAN IMPACT REPRODUCTIVE EFFICIENCY. THIS IS CRITICAL SINCE THE HEALTH AND WELLBEING OF THE CATTLE HERD IN THE UNITED STATES IS PARAMOUNT TO THE US ECONOMY, AND PRIOR INVESTMENTS OF BOTH FEDERAL AND INDUSTRY FUNDS HAVE DEVELOPED EFFECTIVE VACCINES AGAINST BOVINE VIRAL DIARRHEA VIRUS (BVDV) AND BOVINE HERPESVIRUS (BHV-1) THAT ARE EXTREMELY EFFECTIVE AT DECREASING ADVERSE EFFECTS. HOWEVER, RECENT RESEARCH HAS REPORTED THAT THE TIMING OF THE ADMINISTRATION OF THESE VACCINES PRIOR TO BREEDING CAN HAVE NEGATIVE CONSEQUENCES ON REPRODUCTIVE PERFORMANCE. REPRODUCTIVE PERFORMANCE IS OF CRITICAL IMPORTANCE TO THE PROFITABILITY OF COW-CALF PRODUCERS. THUS, TO HAVE OPTIMAL REPRODUCTIVE EFFICIENCY WE NEED TO EVALUATE THE TIMING OF VACCINE ADMINISTRATION AND HOW THEY CAN IMPACT EFFICIENCY.THE OVERALL LONG-TERM GOAL OF THIS RESEARCH IS TO DETERMINE WHEN VACCINATIONS SHOULD OCCUR TO PROTECT THE COW HERD WITHOUT IMPACTING REPRODUCTIVE PERFORMANCE. OUR GENERAL HYPOTHESIS IS THAT GIVEN SUFFICIENT TIME (> 45 DAYS) BETWEEN VACCINATION AND THE START OF THE BREEDING SEASON VACCINATION WILL NOT RESULT IN DECREASED FERTILITY DURING THE BREEDING SEASON.THIS PROPOSAL ADDRESSES THE PRIORITY AREA OF ANIMAL HEALTH AND PRODUCTION AND ANIMAL PRODUCTS.THE SPECIFIC AIM OF THIS PROPOSAL IS:1. TO DETERMINE THE IMPACT OF TIMING INTERVAL BETWEEN VACCINATION (WITH EITHER A MLV OR IV) AND THE START OF THE BREEDING SEASON ON REPRODUCTIVE PERFORMANCE.2. TO DETERMINE CHANGES IN IMMUNE CELL TYPES AND THEIR ACTIVITY FOLLOWING ADMINISTRATION OF A MLV OR IV VACCINE.