A Stochastic Simulation Model for the Efficacy of Vaccination Against Mycobacterium avium subsp. paratuberculosis in Dairy Sheep and Goats

We assessed the benefits of vaccination against Mycobacterium avium subsp. paratuberculosis (MAP) on the average daily milk yield (DMY) of sheep and goat flocks. A stochastic simulation model was used to estimate the DMY pre and post vaccination of the flock replacements. The average DMY increased steadily for the first ten years post vaccination and then reached a plateau. Medians for the DMY were significantly higher post vaccination. The expected difference between the prevalence of MAP infection between and after the initiation of the vaccination program was the most influential factor for the DMY benefits. Vaccination of replacements in a MAP infected flock is expected to improve the overall milk productivity in the long term.