Milk quality assurance programmes for paratuberculosis: stochastic simulation of within-herd infection dynamics and economics

M.F. Weber, H.J.W. van Roermund, A.G.J. Velthuis, A.A. de Koeijer, M.C.M. de Jong, M.W.F. Nielen

Research output: Chapter in Book/Report/Conference proceedingConference paperProfessional

Abstract

A bulk milk quality assurance programme for Mycobacterium avium subsp. paratuberculosis (Map) in dairy herds was simulated. Herds were certified as `low-Map bulk milk¿ if, with a certain probability, the concentration of Map in bulk milk did not exceed a maximum acceptable concentration (MAC). The MAC was based on pasteurisation studies. The programme starts with an intake procedure; test-negative herds enter a surveillance procedure and test-positive herds enter a control procedure. The aim of this study was to simulate different programmes to evaluate their epidemiological and economic effects in a population of closed Dutch dairy herds. Combinations of various herd examinations for the intake, surveillance and control procedure were simulated with JohneSSim (a stochastic simulation model). For example, intake was done by ELISA, surveillance by biennial ELISA and control by biennial faecal culture. Test-positive animals were culled. All programmes were simulated with and without preventive management measures taken by all participating herds. Sensitivity analyses were performed for uncertain parameters. The results show that herd examinations by ELISA for intake and surveillance effectively ensure the quality of `low-Map bulk milk¿: >96% of simulated certified herds (increasing to >99% after 10 years) were below the MAC. Preventive management measures hardly influenced the Map bulk milk concentration of certified herds. However, preventive measures were pivotal to enable herds in the control procedure to move to `low-Map bulk milk¿ status. Culling based on biennial faecal culture was more effective than culling based on annual ELISA. Average total discounted costs for 20-year participation in the programme mentioned above were ¿6×103 per average Dutch dairy herd. On average, additional preventive measures increased these costs to ¿40×103 per herd. This study showed that a bulk milk quality assurance programme for closed Dutch dairy herds is feasible and provided decision-makers with information on the cost-effectiveness of different programmes.
Original languageEnglish
Title of host publicationProceedings of the 8th International Colloquium on Paratuberculosis
EditorsE.J.B. MPH, MBA, DVM Manning, S.S. DVM, PhD Nielsen
Place of PublicationCopenhagen, Denmark
Pages60-73
Number of pages14
Publication statusPublished - 2005
EventA meeting of the International Association for Paratuberculosis, Inc. -
Duration: 14 Aug 200518 Aug 2005

Conference

ConferenceA meeting of the International Association for Paratuberculosis, Inc.
Period14/08/0518/08/05

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