AMINO-ACID PROFILE OF HIGH SEED PROTEIN SOYBEAN

Soybean [Glycine max (L.) Merr.] is used extensively to meet the protein needs of animals and humans. Although a good source of protein, soybean's nutritional value is limited by low concentrations of sulfur-containing amino acids (i.e., methionine and cysteine). Thus, it is often necessary to supplement diets with synthetic amino acids, a practice that ran be expensive and adds complexity to the diet formulation process. The objective of this study was to determine if amino acid concentrations in recent high protein germplasm releases differ from those in normal protein cultivars. The high protein (HP) lines BARC-6, BARC-7, BARC-8, and BARC-9 and a normal protein check, either Essex or Manokin were grown in eight different environments from 1989 to 1991. Seed was analyzed for amino acid concentrations, protein, oil, crude fiber, ash, carbohydrate, and moisture. Protein concentration of HP lines ranged from 495 to 530 g kg(-1). The HP lines were lower in oil, crude fiber, and carbohydrate compared to the checks. Concentrations of 14 of the 17 amino acids differed among entries. Concentration of cysteine of BARC-8, 13.7 g kg(-1), was higher than any other entry. Methionine concentration of BARC-7 (10.8 g kg(-1)) and lysine concentration of BARC-9 (55.0 g kg(-1)) were significantly lower than the checks. Feeding trials are necessary to determine the practical significance of these amino acid differences.