IV. BIOCHEMICAL SYSTEMS 435 



corn and soybean meal, would increase the rate of growth of chicks. These 

 iindings were followed by a report by Gillis and Norris,'*" who also found 

 that either choline or betaine would produce added growth in chicks on a 

 diet of cereals and soybean meal. The addition of 0.16% of "liver paste" 

 containing vitamin Bii activity was even more effective than choline or 

 betaine in improving growth, and if choline or betaine were added in addi- 

 tion to the liver paste, no further improvement in growth was obtained. At 

 about this time, Schaefer and coworkers reported that concentrates con- 

 taining vitamin Iii2 had a sparing effect on the choline requirement of 

 chicks; at 8 weeks the weight gain of chicks receiving 0.2% of choline plus 

 a source of vitamin B12 was equal to that of chicks receiving O.G % of choline 

 without \'itamin Bi2.'°^ Gillis and Norris^"' then showed that vitamin B12 

 behaved in a manner similar to liver paste in replacing the growth-promot- 

 ing effect of choline or betaine under the conditions previously reported 

 by them. 



The effects of \'itamin B12 on the response to choline and methionine by 

 chicks were studied by Jukes and Stokstad.^""* Vitamin Bi2-deficient chicks 

 were fed a purified diet deficient in choline and containing 20 % casein and 

 0.4% cystine with added vitamins including folic acid. Either choline or 

 vitamin B12 markedly increased the growth of chicks on this diet, but 

 maximum growth was not obtained unless both supplements were given, 

 nor was perosis prevented unless 0.15% of choline was added to the diet. 

 The addition of vitamm B12 hastened the onset of perosis. Growth was 

 slower at a level of 0.6% choline than at a level of 0.3% choline, w-hether 

 or not vitamin B12 was administered. A diet containing ground peas, gelatin, 

 and glucose supplemented with choline, tryptophan, and vitamins including 

 folic acid was used for the production of methionine deficiency in vitamin 

 Bi2-deficient chicks. Growth was increased by either methionine or vitamin 

 B12 but was subnormal unless both supplements were given. 



Studies with chicks on a diet deficient in both vitamin B12 and methio- 

 nine were reported by Jukes and coworkers.^"^ The diet consisted of glucose, 

 alcohol-extracted soybean protein, cystine, dimethylaminoethanol, min- 

 erals, and vitamins. Homocystine did not promote the growth of vitamin 

 Bi2-deficient chicks on this diet even when betaine was added, but the 

 chicks responded to the addition of methionine. When supplemented with 



">o O. H. Mishler, C. W. Carrick, and S. M. Hauge, Poultry Sci. 28, 24 (1949). 



'" M. B. Gillis and L. C. Norris, /. Biol. Chem. 179, 487 (1949). 



'02 A. E. Schaefer, W. D. Salmon, and D. R. Strength, Federation Proc. 8, 395 (1949); 



Proc. Soc. Expil. Biol. Med. 71, 202 (1949). 

 >«' M. B. Gillis and L. C. Norris, Poultry Sci. 28, 749 (1949). 

 1" T. H. Jukes and E. L. R. Stokstad, Abstr. Papers 116th Meeting, Am. Chem. Soc. 



p. 40A (1949); /. Nutrition 43, 459 (1951). 

 1" T. H. Jukes, E. L. R. Stokstad, and H. P. Broquist, Arch. Biochem. 25, 453 (1950). 



