A dynamic programming model was developed in which cows were described in terms of lactation number, body weight, 305-day milk yield, and milk fat percent. Milk returns, beef sales, feed costs, replacement costs, and cow depre-ciation costs were included. A 10-yr planning horizon was used. Three prices were assigned to each economic compo-nent and to the interest rate in the discounting procedure. Ninety-five per-cent of the optimal policies were unaf-fected by changes in prices or interest rate. All cows producing less than 4500 kg of 4.1 % milk were replaced. Those producing more than 6500 kg of 3.9% were kept. Optimal policies for other milk yields were dependent on lactation number, body weight, and prices. Increas-ing milk price or decreasing feed price resulted in more intensive culling of lighter cows and less intensive culling of heavier cows. Increasing interest rate re-sulted in less intensive culling for all categories of body weight. The model was insensitive to changes in price of beef. Optimal policies for 94 % of the states did not change with different feeding. With a 5-yr planning horizon, culling was more intensive
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