Amino Acid Content of Noncell and Cell Wall Fractions in Feedstuffs

Abstract

Total and phosphate buffer insoluble amino acids were determined for corn grain and silage, dried brewer's grain, timothy hay, and soybean meal. In addition, amino acid compositions of the acid detergent residue and neutral detergent residue were determined, and soluble amino acids were estimated for each feedstuff. Variation of amino acid concentrations among protein fractions as percent of total amino acid was measured in the buffer insoluble, soluble, neutral detergent fiber, and acid detergent fiber fractions within a feed as well as among feedstuffs. Insoluble noncell-wall, neutral detergent, and acid detergent amino acids as a percentage of total individual amino acid (neutral detergent fiber or acid detergent fiber amino acid/total individual amino acid × 100) for soybean meal, brewer's grain, corn grain, timothy, and corn silage were 73.2, 8.5, 5.6; 31.2, 54.5, 16.3; 72.1, 16.2, 4.6; 18.0, 55.6, 8.2; 14.6, 20.8, and 4.8. Recovery of amino acid nitrogen as percent of total Kjeldahl nitrogen varied among and within fractions studied. © 1983, American Dairy Science Association. All rights reserved.