Availability of Amino Acids in Legumes and Legume-Wheat Blends

Abstract

Availability of amino acids in casein, soybean, field pea or fababean and their blends with methionine, wheat or wheat plus lysine, methionine and threonine was investigated by balance trials with rats. Amino acids in casein or its blends were 95-100% available. The availability values for soybean, field pea and fababean when fed as sole source of protein ranged from 82-95, 75-96 and 70-90%, respectively. In all the legumes, methionine and cystine were less available than other amino acids. Supplementation of the legumes with methionine improved the availability of all amino acids especially methionine and cystine. The availability values in the methionine-supplemented soybean, field pea and fababean ranged from 85-98, 80-99 and 80-98%, respectively. Supplementation of the legumes with wheat exerted a negative effect on the availability of lysine but improved the availability of most other amino acids and the availability differences for all amino acids among soybean (84-96%), field pea (84-94%) and fababean (81-94%) were reduced. Supplementation with wheat plus amino acids further reduced the availability differences among the legumes and the values for soybean, field pea and fababean ranged from 90-98, 88-97 and 88-97%, respectively.