Juvenile Vaccination against Mycobacterium avium ssp paratuberculosis Impacts Incidence and Cull Rates

Abstract

Johne's disease (JD) caused by Mycobacterium avium ssp paratuberculosis (MAP) is significant and costly to dairy producers. These costs manifest from increases in culls and opportunity costs derived from losses in the genetic potential of the herds. Vaccination with the USDA-approved vaccine (Mycopar) between five and 35 days of age reduces the incidence of clinical MAP infection. Limitations of vaccination with Mycopar for MAP are economic losses incurred during the period between vaccination and integration into the lactating dairy herd, and the possibility of vaccinated animals exhibiting continued shedding of bacteria. This pragmatic trial examines the efficacy of Mycopar vaccination in dairy heifers up to 15 months of age on the incidence of clinical Johne's disease.