The economics of culling dairy cows with clinical mastitis

Culling dairy cows with clinical mastitis reduces the incidence of the disease in dairy herds, but the costs of such action, in terms of reduced milk production and increased replacement costs, are generally thought to outweigh the benefits. To test this hypothesis a stochastic dynamic programming model was developed to establish the economically optimum time of replacement for dairy cows subject to variable levels of clinical mastitis infection, using average United Kingdom production and price parameters. The optimal stage at which to replace a dairy cow was found to be sensitive to changes in mastitis incidence and in critical price parameters within the bounds of commercial experience. This result indicates that an objective culling policy based on clinical mastitis records in addition to milk production potential may be economically viable.