Costs and efficacy of management measures to improve udder health at Dutch dairy farms: the use of expertise

Introduction Mastitis is an endemic disease in the dairy sector worldwide and causes, amongst others, serious economic consequences (Halasa et al., 2007). Mastitis expresses itself in two ways: subclinical mastitis and clinical mastitis. To measure the mastitis situation at a farm, bulk tank somatic cell count (BTSCC) is often used as parameter for subclinical mastitis and clinical mastitis (CM) is often expressed as the incidence rate of CM (Barnouin et al., 2005). It is difficult to control mastitis, because it is a multi-factorial disease, has numerous causative bacteria and can be transmitted from cow to cow (contagious mastitis) and from environment to cow (environmental mastitis). The multifactorial nature of mastitis means that there are many risk factors for mastitis, requiring a number of different management measures to control. Literature on the efficacy of management measures mostly gives general information which is not applicable in a farm specific situation, especially when the effects need to be quantified for economic calculations. Quantitative data on continuous variables are usually a prerequisite for sound decision making. Preferably, such data are derived from field studies and experiments. However, these data often are not (yet) available or, if available, incomprehensive, unreliable, only indirectly applicable or a combination of these factors. This results in decisions being made without correct and complete information. In such situations, expert judgement is the only way to gain the required knowledge (Seabrook, 1984).