AbstractThis paper is based on the winning entry in the Operational Research Competition for Schools 1979. It examines the winter feed costs for dairy cattle on a Devon farm. The present feed is investigated using computer assisted optimisation techniques. The paper then examines whether silage should be introduced; the possible savings and necessary capital costs are calculated. In conclusion it proposes that the present feed be reduced and silage introduced as the main constituent, giving an initial annual saving of£13,000. The proposals are being seriously considered by the farmer and may be implemented in the near future.