508 VITAMIN Bi2 



contents had a marked effect in improving the growth of chicks and turkeys 

 when added to diets consisting principally of ground wheat, soybean meal, 

 and alfalfa meal. Studies by Hammond and Titus'' indicated that on similar 

 diets the early growth of chicks was improved by adding 2 % of sardine 

 fish meal to the basal mixture. 



At first it was suggested that androgens and riboflavin were the factors 

 principallj^ involved in the growth-promoting effects of cow manure, but 

 later it became apparent that an unknown vitamin-like substance, the "cow 

 manure factor," was largely responsible for remedying the deficiency which 

 existed in the vegetable diet. Thus was foreshadowed the eventual develop- 

 ment which led to the industrial production of vitamin B12 by microbial 

 fermentation, for it is the microflora of the digestive tract of the cow which 

 lead to the presence of the vitamin in the feces and rumen contents. 



The investigations started by Hammond and Titus were continued by 

 Rubin and Bird,^ who prepared concentrates of the cow manure factor and 

 carried out experiments which further differentiated it from the known vi- 

 tamins including folic acid and vitamin Be. The factor was concentrated 

 from cow manure to some extent by extraction with acid and precipitation 

 with ammonium sulfate. The Belts ville group explored widely the nutri- 

 tional relationships of the factor as regards growth and hatchability. It was 

 shown that a deficiency of the factor as measured by hatchability of eggs 

 or by chick growth was accentuated by increasing the soybean meal con- 

 tent of the diet.^'' This observation provided a point of similarity with the 

 factor X of Gary and Hartman, the requirement for which had been shown 

 to be increased by adding soybean meal or alcohol-extracted casein to the 

 basal diet. The use of a diet containing 70 % of soybean meal made it more 

 easily possible to produce the deficiency experimentally in chicks. However, 

 an even more important consideration was found to be the carry-over of 

 the factor from the maternal diet through the egg into the chick. When hens 

 received diets containing from 5 to 10 % of fish meal, their offspring were 

 found to grow quite rapidly on all-vegetable diets. In contrast, when hens 

 were placed on all-vegetable diets the hatchability of their eggs tended to 

 diminish, and the chicks which hatched grew slowly on the basal diet unless 

 they were supplied with a dietary source of the factor. 



Bethke and coworkers^- ^^ found that a diet in which soj'bean meal was 

 the only source of supplemental protein was adequate for egg production 

 but lacked a factor for hatchability which was present in pork liver, liver 

 extract, fish solubles and, to a lesser extent, meat scraps. When chicks 



7 J. C. Hammond and H. W. Titus, Po7iUnj Set. 23, 49 (1944). 

 8M. Rubin and H. R. Bird, /. Biol. Chem. 163, 393 (1946). 

 8° D. Whitson, H. W. Titus, and H. R. Bird, PouUry Sci. 25, 52 (1946). 

 9 R. M. Bethke, D. C. Kennard, and V. D. Chamberlin, Poultry Sci. 25, 589 (1946). 

 >» R. M, Bethke, J. M. Pensack, and D. C. Kennard, Poultry Sci. 26, 128 (1947). 



