The Metabolism of Raw Versus Heated Soybeans in Birds with Colostomies

SOYBEANS have a growth inhibitory effect which has puzzled investigators for many years. Long ago Osborne and Mendel (1917) found that this growth inhibition could be largely eliminated by heating the soybeans. Succeeding investigators, Mitchell and Smuts (1932), Hayward, Steenbock and Bohstedt (1936 a, b), Hayward and Hafner (1941), and Almquist, Mecchi, Kratzer and Grau (1942) found that the addition of sulfur containing amino acids, cystine or methionine, to the diets reversed the inhibition. Shrewsbury, Vestal and Hauge (1932) concluded from their results that the beneficial effect of heat upon soybeans was due to increased food consumption, with a slight increase in digestibility of the nitrogen. Johnson, Parsons and Steenbock (1939), reported essentially the same digestibility of the nitrogen and sulfur in heated or raw soybeans. They suggested from sulfur balance studies the existence of an unavailable sulfur compound in raw soybeans which was absorbed and excreted in the urine. . . .