Methionine Supplementation of Processed Soybeans in the Rat

Publisher Website
Google Scholar
Abstract
The methionine requirement of the rat under conditions where cystine was not limiting has been established as 0.17 to 0.19% of “available” methionine in the diet. The term “available” indicates that a correction for differences in intestinal absorption has been applied. The methionine requirement was found to be the same when the basal diet supplied either 15 or 25% protein in the form of isolated soybean protein. Under these conditions the second limiting amino acids were provided at adequate levels for maximal growth even at the lower protein intake so that it would be expected that the methionine requirement would not be changed by these levels of protein. The normal methionine requirement was provided by unheated soyflakes at 50% of the diet. Added free methionine increased maximal growth with 50% of unheated soyflakes, but no growth stimulation was obtained by methionine added to a diet containing 70% of unheated soyflakes. A tentative conclusion has been drawn that the growth inhibitor factor in unheated soyflakes decreases tissue utilization of methionine and that this is not a general inhibitory effect upon the utilization of all amino acids.