Unidentified Factor Activities in Whole Soybeans Required for Optimum Growth of Coturnix Quail

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Abstract
Coturnix quail chicks fed an amino acid diet with a ratio of 115 kcal metabolizable energy per kilogram of diet for each 1% protein survived and tripled their body weight in 10 days. An average of five experiments showed that growth was increased by 35% when isolated soy protein was substituted on an equivalent amino acid basis for a portion of the amino acids and starch. When heated, ground whole soybeans were substituted, growth was increased an average of 54%. Five experiments were conducted to evaluate the basal diet and fractionate the soybean protein. The basal diet was shown to be adequate in all known nutrients. Fractionation and hydrolysis of soybeans and soy protein indicated the presence of two growth promoting factors in ground soybeans. One growth promoting factor was present in the isolated soy protein precipitated at pH 4.7 to 4.8. Another factor was in the whey fraction after the precipitated protein was removed. Enzymatic hydrolysis of the ground soybeans or the soy protein with papain did not affect the growth promoting properties of either fraction. However, the growth promoting effect was completely lost when these materials were subjected to a sequential hydrolysis using papain, pepsin, and trypsin. Partial hydrolysis of soy protein with trypsin followed by removal of the undigested protein according to the method for the preparation of strepogenin (J. Biol. Chem. 174: 71, 1948) gave a product which retained most of the growth promoting activity of the original isolated soy protein. Results showed that the amino acids in soybeans were not responsible per se for the growth effect. The results suggest that quail chicks fed an amino acid diet require certain peptides for maximum growth.