436 VITAMIN Bi2 



vitamin B12, the chicks responded to methionine or homocystine. These 

 results were interpreted as indicating that vitamin B12 is involved in the 

 transformation of homocystine to methionine in chicks. 



Interrelationships between vitamin B12 and various precursors of choline 

 were studied in chicks by Schaefer et al}^^ The basal diet consisted of 

 extracted peanut meal, sucrose, extracted casein, lard, cystine, minerals, 

 and vitamins. Some results are shown in Table IV; vitamin B]2 where in- 

 cluded was added at a level of 30 7 per kilogram of diet. The absence of 



TABLE IV 



Effect of Choline and Related Compounds on 4-Week Weight Gains, Perosis, 

 AND Mortality in Chicks"^ 



appropriate controls without vitamin B12 makes it difficult to interpret the 

 data completely; however, the authors conclude that vitamin B12 appeared 

 to be involved in the synthesis of choline from methylaminoethanol in the 

 presence of methionine or betaine as judged by the ability of these combina- 

 tions to replace choline when vitamin B12 was added to the diet. It was 

 also noted that even when vitamin B12 was added aminoethanol plus 

 betaine could not serve as precursors of choline as judged by growth re- 

 sponse and the prevention of perosis. 



In 1950 Briggs and coworkers^"^ used non-depleted chicks fed 'practical- 

 type" diets consisting principally of corn and soybean meal. They found 



'oe A. E. Schaefer, W. D. Salmon, and D. R. Strength, /. Nutrition 44, 305 (1951). 

 1" G. M. Briggs, E. G. Hill, and M. J. Giles, Poultry Sci. 29, 723 (1950). 



