An economic model to estimate farm-specific losses due to bovine respiratory diseases in dairy heifers

Bovine respiratory disease (BRD) is a broad term that embraces a range of respiratory diseases, caused by a wide variety of micro organisms (essentially viruses and bacteria). The disease leads to considerable losses among cattle, especially in younger animals. These losses include the cost of treatments (medicines and veterinary visits) and losses associated with the effects of the disease on the current and future performance of the animals affected ('performance effects'). The performance effects following BRD in dairy heifers include an increased probability of death and culling, depressed growth rates, an increased age at first calving and (possibly) a decreased milk production in first lactation (Correa et at., 1988; Donovan ct at., 1998; Virtala et at., 1996; Waltner-Toews et al., 1986; Warnick ct al., 1995). Information on the presence and, in particular, on the impact of these effects is scarce and, if available, often contrary. This makes it hard to calculate the total losses due to BRD in dairy heifers. Despite this lack of knowledge, farmers together with their veterinarians frequently have to make decisions with respect to the on-farm control and prevention of BRD. In order to make better and economically sound decisions they need to have more insight into the economic impact of the disease on their farm. To provide this insight a computer model is developed to estimate the farm-specific losses due to clinical BRD in dairy heifers in the Netherlands. In this paper the outline of the model as well as some preliminary results are presented.