An economic model for on-farm decision support of management to prevent infectious disease introduction into dairy farms

A more-closed farming system can be a good starting point for eradication o f infectious diseases from within a herd. The economic implications of a mo re-closed farming system will not always be obvious to farmers. The managem ent decisions are related to different parts of the farm and are farm-speci fic. To support these decisions, a model was developed of the economic cons equences of a more-closed system (a simple static and deterministic design was used). The risk factors in the model were based solely on bovine herpes virus type 1 (BHV1) but losses due to introduction of BVDV, L. hardjo, and S. dublin were added to the model. The model was verified and partly valida ted and a sensitivity analysis was done. The cost to one 55-cow dairy farm that refrained from purchasing cattle, pr ovided protective clothing to professional visitors and a temporary employe e, and built and maintained a double fence a-round 6 ha of land to prevent over-the-fence contacts was Dfl. 4495 over 5 years. The probability of dise ase introduction was decreased by 74%. The prevented losses for disease int roduction amounted to Dfl. 7033 over 5 years (net benefits of Dfl. 2538 ove r 5 years). A more-closed system would be still beneficial when a sanitary barrier was used instead of just protective clothing, when the probability of introduct ion of infectious diseases was decreased, and when odds ratios in the model were replaced by more-conservative relative risks. The benefits became neg ative when a farm had to build and maintain a double fence around 12 ha ins tead of 6 ha, when the probability of introduction of all diseases was decr eased by 50%, and when the estimations were based solely on BHVI. (C) 2001 Elsevier Science B.V. All rights reserved.