Risk analysis and economic consequences of a more or less closed farming system on Dutch dairy farms

A more closed farming system may prevent introduction of infectious diseases on dairy farms and can be a good starting point for eradication of these diseases. In an exploratory study it was calculated that being >open= had a negative influence on net profit of almost Dfl 1 per 100 kg of milk. A survey was carried out to make up an inventory of the existing more or less closed farming systems in the Netherlands. The associations between serologic status for BHV1, risk factors for introduction of diseases, management, and economic results were investigated. A follow-up cohort study with 100 dairy farms will be carried out to quantify the determined associations and prove possible causal relationships. Three groups of farms will be selected, a group which is as closed as possible, a group which is open, and a group in-between, closed for animal contacts but not for visitors and materials. The groups will be compared on introduction of infectious diseases, management, factorial diseases and economic results. The results of the project will be used to create a computer model which can be used to support farmers in their decisions to derive a more or less closed farming system to prevent introduction of diseases.