Multiple Amino Acid Supplementation of White Corn Meal

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Abstract
A white corn meal diet was supplemented with graded levels of lysine and tryptophan in an experiment of incomplete factorial design based on the ratio and the product of the two first limiting amino acids. From the growth and efficiency of food utilization of weanling rats receiving the 18 different combinations used, the amounts of lysine and tryptophan required for optimal results were calculated. Maximal performance was predicted to occur at a ratio of 5.5 to 1 for lysine to tryptophan. This result confirmed the 5:1 ratio suggested by Rose. Methionine, threonine, isoleucine and valine were evaluated as the third limiting essential amino acid in corn. The addition of none of these singly improved the growth of the weanling rat fed the corn meal diet, appropriately supplemented with lysine and tryptophan. Among the combinations of two of these amino acids only threonine and isoleucine caused an appreciable response, suggesting that these two amino acids are about equally limiting in corn. Under the conditions of these experiments no evidence for a leucine-isoleucine antagonism was observed.