Amino acid absorption along the intestinal tract of chicks fed heated and raw soybean meal.

Net absorption of individual amino acids along the intestinal tract was determined in chicks fed heated soybean meal (HS) and raw soybean meal (RS) using 91Y as a reference substance. In the duodenum of chicks fed either diet, the absorption of the amino acids varied. In chicks fed the RS diet, the differences were greater than in chicks fed the HS diet, and most of the values were negative. Methionine was the most rapidly absorbed amino acid. No cystine was found in the upper parts of the intestinal tract of chicks fed either diet. A linear relationship was obtained between the amino acid absorption values in the duodenum of chicks fed either diet. The differences recorded seem to be due to nitrogen secretion, which is enhanced in RS-fed chicks. The differences between individual amino acid absorption decreased gradually in the other segments and attained in the lower ileum an average cumulative value of 90% and 70% in chicks fed on HS and RS respectively. The 20% difference was probably a result of the inhibited digestion in the intestine (duodenum excluded) of chicks fed RS. The results indicate that the absorption process can proceed even when the digestion is inhibited.