One objective of the NAHMS Dairy '96 Study was to assess dairy producer awareness of Johne's disease, estimate national and regional herd-level prevalence of Mycobacterium paratuberculosis infection, estimate economic losses due to Johne's disease on dairy operations, and describe use of recommended preventive measures on U.S. dairy operations. Data were collection from U.S. dairy operations with at least 30 milk cows in 20 states representing 79.4 percent of U.S. dairy cows via questionnaires administered to dairy managers and blood samples collected from milk cows by Veterinary Medical Officers and Animal Health Technicians. Sera were tested for antibodies to M. paratuberculosis using a commercially available ELISA. Results showed lack of widespread recognition, testing, and use of herd certification programs for Johne's disease by U.S. dairy producers. From serologic testing and use of herd historical information, the best estimate of herd infection prevalence of M. paratuberculosis on U.S. dairy operations was 21.6 percent. Herd size differences were apparent, however, with higher infection prevalence in larger herds. Economic analyses showed the annual adjusted value of production was over $200 per cow for positive herds with at least 10 percent of their cull cows showing clinical signs consistent with Johne's disease. Contact for this paper: Steven Ott
