Meat and Bone Meals as Sources of Amino Acids for the Growing Rat: Use of a Reference Diet to Predict Amino Acid Adequacy by Levels of Plasma Free Amino Acids2

LEVELS of free amino acids in the plasma should be excellent response criteria for predicting the limiting amino acids and availability of amino acids from different proteins. The use of concentrations of free amino acids in the plasma takes into account digestibility and availability which are not known when amino acid adequacy is predicted from chemical analysis of protein. A suitable reference diet will contain neither excesses nor inadequate amounts of amino acids and will support maximal performance of the test animal to establish baseline or reference levels for each of the amino acids in the plasma. Two experiments were conducted to determine dietary deficiencies and excesses of amino acids in meat and bone meals from different origins by comparing the plasma free amino acid levels of rats fed the meat and bone meal diets with those of rats fed caseinamino acid reference diets. The effect of reducing the levels of certain amino acids in the reference diet on predicting dietary deficiencies and excesses of amino acids in the meat and bone meals was determined.