Least-Cost Formulations Linear programs on computers have made it possible to design diets that will meet all minimum nutritional requirements of swine at the least cost. Least-cost formulation techniques are helpful to feed manufacturers and pork producers who maintain inventories of a large number of ingredients or who frequently purchase and sell large quantities of them. Least-cost programs usually select the combination of ingredients that give the lowest cost for the diet, not necessarily the ones that result in the lowest cost per unit of gain. Least-Cost Alternatives Energy sources, protein, and phosphorus are the three most costly items of the total diet. Ingredients which supply energy make up the major portion of any swine diet and usually account for the majority of the cost of that diet.
Feed grains are typi- cally used as the major source of dietary energy for all classes of swine.
Each type of grain has certain unique physical and chemical characteristics which affect its value as swine feed. The second major cost of diets is incurred from supplemental proteins. Actually, it is the lysine in the protein source that determines the amount of the protein source needed in most swine diets. The percentage of lysine found in grain varies considerably, and it is not directly related to the percentage of protein found in the grain. Because of this, swine diets should be formulated and ingredients evaluated on a lysine rather than protein basis.