Risk factors for bovine respiratory disease in dairy youngstock in The Netherlands : the perception of experts

This paper describes a study aimed at quantification of expert opinion on risk factors for clinical bovine respiratory disease (BRD) in dairy youngstock in The Netherlands. For this purpose, a panel of 21 experts working in the field of BRD was selected. Total expert consultation consisted of five different rounds and included four rounds that comprised questionnaires held by mail and a 1-day workshop (last round). During the expert consultation different elicitation methods were used, such as the Delphi procedure and Adapted Conjoint Analysis (ACA). The most important risk factor for, respectively, mild and severe pneumonia in dairy calves aged 0-3 months was perceived to be (poor) air circulation and purchase of cattle. The latter risk factor was also considered as having the highest impact on the incidence of severe outbreak cases in dairy youngstock aged 3-6 months, whereas a previous case of BRD was considered to be the most important risk factor for mild outbreak cases. Outbreaks (both mild and severe) in dairy youngstock aged 6-24 months were perceived to be influenced most by air circulation