Probable Identity of Unidentified Chick Growth Factors in Fish Solubles and Penicillin Mycelium Residue

Abstract Evidence indicating the existence of at least two chick growth factors not identical with any of the known vitamins has been presented. Fish solubles have been reported to be a source of unknown growth factors in experiments with chicks fed diets believed to be adequate in all known nutrients. In an investigation conducted at this institution, studies have been made of the relative value of fish solubles and penicillin mycelium waste as sources of unidentified chick growth factors. The results of two experiments which show that these materials are qualitatively of approximately comparable value are presented in this report. White Leghorn day-old male chicks were used in the experiments. Each lot contained twenty chicks at the start. The chicks were weighed individually at the beginning of the experiment and weekly thereafter. A weekly record of feed consumption was made. The experiments were concluded when the chicks were four weeks old… .