OPTIMAL DAIRY COW REPLACEMENT POLICY

The culling decision is made before a lactation commences, the decision-maker being faced with the choice of retaining a cow for further production or replacing her. A simple dynamic programming model is developed to find the optimal culling policy in terms of expected future returns from milk and butterfat production. A stochastic factor is included in the form of the probability that a cow will survive or succeed in a given lactation. The model is run for the 20-year period 1957-76 and the solution remains quite stable with application of different probabilities and production patterns. We conclude that the optimal culling rate for the period is between 1/5 and 1/6 which is close to the actual rate.