The Complex Nature of the Animal Protein Factor

Abstract

Pure vitamin B12 has been reported by several groups of workers to promote growth responses in chicks, under their experimental conditions, comparable to those obtained with crude sources of the animal protein factor. The experiment reported here, however, furnishes evidence for the existence of additional factors in fish meal and in some batches of dried brewers’ yeast. The basal diet fed in this experiment consisted of 23.5% alpha-protein (The Glidden Company), 65.0% cerelose, 2% soybean oil, 3% cellophane, 0.3% L-cystine, 0.3% D-L methionine, 0.3% glycine, 1% fish liver oil (2000 AOAC units of vitamin A and 400 IU of vitamin D per gram), 1.1% pulverized limestone, 1.7% dicalcium phosphate, 0.8% dibasic potassium phosphate, 0.5% salt, 0.5% magnesium sulfate and the trace minerals and vitamins as described by Hill et al. (1944) except that the thiamine HC1 was increased to 1 mg and 50 μg of folic acid and 1.16 μg . . .