The Free Amino Acid Pattern of the Intestinal Contents of Chicks Fed Raw and Heated Soybeam Meal

Abstract

Free amino acid (FAA) patterns were investigated in ultrafiltrates of intestinal contents and plasma of chicks fed raw soybean (RS) and heated soybean (HS) meals at two levels in the diets. The intestinal FAA levels were much lower in the RS than in the HS group. The differences were particularly pronounced with seven essential amino acids: valine, cystine, methionine, isoleucine, leucine, tyrosine and phenylalanine. The HS/RS ratio for these amino acids at the 22% protein level was twice that at the 15% protein level. The electrophoretic separation of the soluble intestinal proteins revealed the presence of protein fractions in the intestinal contents of the 22% RS group, which were not detected in the 15% RS group. The FAA pattern in the plasma from the hepatic portal vein was a clearer reflection of the intestinal FAA pattern than was that of the heart blood plasma. The differences between HS and RS were less pronounced in the blood than in the intestine. The possibility of inhibited protein digestion by RS meal is discussed.