Prediction of Protein Nutritive Value of Cereal-Legume Blends Using Rat Bioassays and Amino Acid Scores

Abstract

Cereal grains and root crops provide the major portion of the world food supply, resulting in widespread deficiencies in dietary protein and essential amino acids. The utilization of legumes and oilseed meals to overcome the lack of lysine, tryptophan and threonine requires high levels of protein supplementation and introduces the problem of methionine deficiency. These dicotyledonous protein sources contain flatulence and antinutritive factors which limit protein utilization and raise protein requirements even further. Amino acid scores (chemical scores) based on the amino acid requirements of the rat gave excellent prediction of feed intake, weight gain, protein efficiency ratio and true biological value in rat bioassays of cereal-legume blends. It is suggested that AA scores based on the amino acid requirements of the human would represent the protein nutritive value more accurately than the rat bioassay. Variations in the digestibilities of the cereal-legume blends examined in this study indicate the need for a specific measure of digestibility as a correction factor for AA score.