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Decisions on whether to cull or to retain for further production are of major importance in all classes of stock farming. Although there have been several studies relating flock composition to culling, reproduction and death rates,l none of these have attempted to compare the profitabiEity of various culling policies, their objective being only to show how flock composition and numbers of stock available for culling vary with variation in reproduction and death rates. Clearly, for given basic population parameters and a given framework of fixed farm resources, there should be a culling policy which is optimum for the particular farm. This note presents a linear programming model which can be used to determine the optimum culling policy for a Romney breeding flock.2For any age class of stock, the decision on whether to cull or to retain for further production depends basically on three factors:(i) The price that can be obtained for the cull animal.(ii) The expected future production if the animal is not culled and the prices that can be expected for the products, (iii) The animal's expected resource requirements over the future production period. With a breeding flock, the expected future production comprises wool and lambs. Unless lambing percentages are abnormally low, there are more young stock coming forward each year than are required to maintain ewe flock numbers. Thus, a certain number of stock must always be sold-assuming fixed carrying capacity, labour supplies, etc. The decision is, how many animals of each particular age class should be sold?3

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