Some thoughts on amino acid supplementation of proteins in relation to improvement of protein nutriture.

Abstract

Supplementation of diets with free amino acids has not routinely been beneficial and poses a potential risk. Thus, mixing proteins to increase the quality of the dietary protein is attractive. The slope-ratio technique for evaluation of protein quality has serious drawbacks, because the growth response is not linear and animals appear to adapt to the diet and thus make more efficient use of diets low in protein or low in protein quality. Apparently, the relative value of proteins is not constant, but varies with the amino acid spectrum as well as intake. Thus, evaluation of proteins or protein mixtures should be determined under the conditions (e.g. maintenance or maximum gain) of their potential use. This approach could lead to the development of a protein replacement equivalents system similar to the starch equivalents system in the evaluation of the net energy of animal feeds.