Research Progress Report 164 February, 1965
Least Cost Rations for Growing and Finishing Swine
R. B. Harrington, R. A. Pickett, T. W. Perry and C. H. Noller, Department of Animal Sciences
Summary
	Under the price conditions used in this experiment, pigs fed the typical fortified corn-soy type rations gained no faster than 2 of the 3 lots on the programmed rations, but feed requirement per pound of gain was less. Feed cost per pound of gain for the pigs on the fortified corn-soy ration is similar to that in 2 of the 3 programmed lots.

	Perhaps one of the most important findings of this research is the indication that pigs can utilize a programmed type ration efficiently. Thus when prices are too high for one ingredient, another more economical source may be used. This puts the matter of swine feeding in the area of science so that a ration is formulated on the basis of amino acids, vitamins, minerals and energy. Common feedstuffs such as corn, soybean meal or meat scraps tend to lose their identity as feedstuffs but rather they are evaluated on the price per unit of amino acids and energy, etc.
The most expensive controls put upon the computer were, (a) minimum energy,
(b) maximum fiber, (c) minimum lysine (amino acid), (d) minimum tryptophan
(amino acid) (e) minimum methionine (amino acid).
Introduction
	Linear programming, when applied to formulating a swine ration, is a process in which the least cost combination of ingredients is put together which will produce satisfac -tory results. By this process, all common feed ingredients such as corn, soybean meal, etc. are reduced to their chemical makeup and are described in terms of carbohydrates, fats, proteins (more specifically, amino acids), minerals and vitamins. The theory which gives living breath to the linear programming of rations is that there is no "one best formula", and that there is a great deal of interchangeability possible among various feeds. In order to follow this line of reasoning, one must assume that any single available amino acid, for example, is as valuable to an animal as the same available amino acid from another source. In other words, there must be a complete interchange of basic nutrients among sources, else linear programming would be of no value.

	Naturally, there must be certain feeding situations where complete interchange-ability of nutrients from various sources is

PURDUE UNIVERSITY • Agricultural Experiment Station • Lafayette, Indiana