Unidentified Factors in Poultry Nutrition

PRIOR to the isolation of vitamin B12, chick growth responses have been obtained with whey, distillers’ dried solubles, dried brewers’ yeast and fish meal. Much of this work has been reviewed by Combs (1951) and Menge et al. (1952a). After crystalline vitamin B12 became available it was possible to determine if all or part of the growth response produced by various feedstuffs could be explained on the basis of vitamin B12 content. In the presence of vitamin B12 in the basal diet, an unknown growth factor was observed in whey by Hill and Branion (1950), Johnson (1950), Arscott and Combs (1950), Reed et al. (1951), Menge et al. (1952a) and Fuller et al. (1952); in liver by Sunde et al. (1950a), Savage et al. (1950), and Menge et al. (1952a); in dried brewers’ yeast by Carlson et al. (1949) and Menge et al. (1952a); in fish meal by Carlson et al.…