Methods for Determining Amino Acid Availability of Feeds

Abstract

ALTHOUGH protein values have been well established and amino acid values are rapidly being determined for feeds, there is limited information concerning biological availability of individual amino acids in grain and protein concentrates. Price et al. (1953) employed chick carcass and excreta analysis to evaluate dietary amino acids and proteins. It was shown that neither dietary level nor age of chick markedly affected the content of the various amino acids of the carcass. However, excreta from chicks fed high protein diets were higher in certain amino acids when compared to excreta from those fed low protein diets. De Muelenaere et al. (1967) determined lysine availability of cereal products by fecal and growth analysis. These workers concluded that growth analysis often yielded values which exceeded 100% and that method of evaluation may influence availability values. For the above reasons it appeared that a measurement of digestibility or the actual disappearance of…