Evidence of New Growth Factors For Chicks

SINCE 1925 a rather extensive amount of literature has been published concerning the chick requirements for factors in the vitamin B complex. This literature has been recently reviewed by Ewing (1941). Little progress has been made since 1940 in the differentiation of new factors which may exist in this complex. Experiments by various investigators designed to determine the riboflavin requirements of chicks have given results which not only show lack of agreement but many inconsistencies. Studies at this station have revealed that results which are usually attributed to riboflavin might be due to other factors. Widaman (1940) showed that when chicks were fed a diet which contained corn, wheat, bran, minerals, cod liver oil, and casein, satisfactory growth was obtained. However, when casein which had been extracted with ether and ethanol was used, growth was markedly retarded. The addition of a riboflavin concentrate2 at a level of 2 percent to . . .