An Evaluation of the Timing of Pre-Breeding Vaccination with a Modified Live Virus Vaccine and its Effect on Fertility in Beef Cattle

Abstract

The use of modified live virus (MLV) vaccines incorporated as a pre-breeding management tool in beef herds is increasingly popular. There are a number of reasons why MLV vaccines are being used. Recent evidence suggests that pre-breeding use of MLV vaccines provides a broader immune response involving both cell-mediated and humoral immunity. Additionally, it is believed that immunity from MLV vaccines extends to at least a year, while killed virus vaccines (KV) are thought to provide a shorter duration of immunity. As well, vaccination of open cows pre-breeding with an MLV bovine virus diarrhea (BVD) vaccine optimizes immunity prior to the critical risk period of fetal exposure to field-BVD virus during the first trimester of pregnancy.