Abstract
From the results of this study it is apparent that the injection of crystalline B12 into poults fed an all-vegetable protein (soybean oil meal-corn) diet failed to have any effect on growth, although such an injection did promote the growth of poults fed aureomycin. Poult growth was stimulated by the feeding of aureomycin, streptomycin, an APF concentrate containing aureomycin, liver “L,” and fish meal and fish solubles. It is believed that the increase in growth associated with the feeding of aureomycin and streptomycin was through an effect of the antibiotic on the microflora of the gastrointestinal tract. The APF concentrate, liver “L” and fish meal and fish solubles were postulated to contain unidentified factors required for poult growth. Supplementation of the basal diet with 8 crystalline B vitamins promoted the growth of poults in some instances but failed to have an appreciable effect in the presence of streptomycin and B12 or when the aureomycin APF was fed. A possible explanation for the latter is presented. The data suggest that the favorable effect of the antibiotics on the microflora of the intestinal tract may have brought about additional synthesis of B vitamins, and that the latter may be a possible explanation for the failure of a growth response to B vitamins in the presence of streptomycin or aureomycin APF.