Essentiality of amino acids for the growing kitten.

The effect of deleting each of the amino acids known to be essential for the young rat was determined in post weanling kittens fed a purified diet containing only L-amino acids as the source of dietary nitrogen. When any one of the 10 amino acids (arginine, lysine, histidine, isoleucine, leucine, methionine, phenylalanine, threonine, tryptophan, valine) were deleted from the diet food intake decreased, the kittens lost weight, and there was a dramatic drop in each corresponding amino acid in the blood plasma; indicating that each of the above amino acids is essential for the kitten. Deletion of all the amino acids except the 10 essential amino acids plus alanine resulted in a decreased weight gain to about 1/3 normal; indicating that although all the other amino acids could be synthesized, one or more of the dispensable amino acids may be required for maximal growth. When any one of the essential amino acids was decreased to one-half that present in the basal diet, there was no decrease in weight gain, indicating that the high protein requirement of the kitten is not the result of an unusually high requirement for the essential amino acids.