The multiple nature of the animal protein factor.

Various studies in poultry nutrition have indicated that certain diets based on vegetable products are deficient in a hatchability-promoting or growth-promoting factor which is associated with certain animal protein materials (l-4). Hammond and Titus (5) studied the effect of a diet of corn, soy bean meal, alfalfa meal, butyl fermentation residues, minerals, and vitamin Ds on chicks and found that growth was improved by adding 2 per cent of sardine meal. The term “animal protein factor” has been used for the dietary factor which is needed for the growth of chicks on diets consisting principally of corn and soy bean meal (6-8). Later work with the diet of Hammond and Titus showed that dried cow manure had an effect similar to that of sardine meal in promoting growth (9). The studies by Hammond el al. were continued by Bird and coworkers who noted that the dietary deficiency was accentuated by increasing the dietary level of soy bean meal to 70 per cent (10). It was also found that the storage of the protective factor in newly hatched chicks was markedly reduced by limiting the supply of the factor in the diet of the parent hens (11, 12). Recently, it was shown by Ott and coworkers (13) that “vitamin Blz” was effective in promoting the growth of chicks on a diet which was deficient in the “animal protein factor.” This finding was confirmed by Lillie and coworkers (14), who concluded that crystalline vitamin Blz was completely effective when tested with chicks and a cornsoy bean meal diet as described by Bird and coworkers (15). In the present investigation, it was found that chicks on a corn-soy bean diet appeared to require some other factor in addition to vitamin Blz for maximum growth.