580 NIACIN 



in the basal diet and hence do not represent the absolute try[)tophan re- 

 (luirement. The fifi;ures listed, both for nicotinic ac^d and tryptophan, can 

 be regarded as valid only under the particular conditions of the experiments 

 cited, in view of the well-known conversion of tryptophan to nicotinic acid 

 and the many other factors whi(;h influence re(iuirem{Mits. 



As indicated in Table XVII, rats, mice, cotton rats, dogs, swine, rabbits, 

 monkeys, chickens, turkeys, ducks, and cats require a dietary source of 

 nicotinic acid except, in some species, when sufficient tryptophan is sup- 

 plied. Fox puppies require nicotinic acid (0.39 to 2.0 mg. per kilogram of 

 body weight per day).^^ The activity of tryptophan has not been reported 

 in this species. Guinea pigs rec^uire nicotinic acid.^^' •"* Banerjee ei al.^^ could 

 demonstrate no activity with tryptophan, although Cannon and associates''^ 

 obtained some evidence that tryptophan could substitute for nicotinic acid 

 and Henderson et al?^ found that tryptophan increased the urinary excre- 

 tion of nicotinic acid and related compounds in guinea pigs. 



Calves,'^"''- horses,"*' ■ ^"* and sheep'''' "^^^ ''^ do not require a dietary source 

 of nicotinic acid, although they can convert tryptophan to nicotinic acid. 



a. Tryptophan 



The conversion of tryptophan to nicotinic acid is described in detail in 

 Section VI. Tryptophan may be added to the diet either as the pure amino 

 acid or as protein. Thus, dogs will develop blacktongue on a 20% casein 

 ration but will not if the casein is increased to 42 %.'' Rats develop ni(;otinic 

 acid deficiency on 9 % casein, cystine-supplemented rations but do not if 

 the casein level is increased to 15 to 25%.''''*^"*' Swine develop nicotinic 



34 R. Bernard and J. M. Demers, Rev. can. biol. 8, 504 (1949). 



35 A. C. da Silva, Acta Physiol. Latinoamer . 1, 20 (1950); A. C. da Silva, K. Fried, 

 and R. C. dc Angelis, J. Nutrition 46, 399 (1952). 



38 A. E. Schaefcr, C. K. Whitehair, and C. A. Elvehjem, J. Nutrition 34, 131 (1947). 

 " M. D. Cannon, G. J. Mannering, C. A. F]]vehjcm, and E. ]i. Hart, Proc. Sac. Exptl. 

 Biol. Med. 63, 414 (1946). 



38 S. Banerjee, R. Banerjee, and C. C. Deb, Indian J. Med. Research 38, 161 (1950). 



39 L. M. Henderson, G. B. Ramasarma, and B. C. Johnson, J. Biol. Chciti. 181, 731 

 (1949). 



"» B. C. Johnson, A. C. Wiese, H. II. Mitchell, and W. B. Nevens, J. Biol. Chem. 167, 



729 (1947). 

 " B. C. Johnson, Euclides {Madrid) 8, 161 (1948). 

 42 G. C. Esh and T. S. Sutton, J. Dairy Sci. 31, 909 (1948). 

 " J. W. Huff, P. B. Pearson, and W. A. Perlzweig, Arch. Biochem. 9, 99 (1946). 

 ■•^B. S. Schweigert, P. B. Pearson, and M. C. Wilkening, Arch. Biochetn. 12, 139 



(1947). 

 « A. H. Winegar, P. B. Pearson, and H. Schmidt, Science 91, 508 (1940). 

 « P. B. Pearson, A. H. Winegar, and H. Schmidt, ./. Nutrition 20, 551 (1940). 

 " J. M. Hundley, ./. Nutrition 34, 253 (1947). 

 « W. A. Krehl, L. J. Teply, and C. A. Elvehjem, Science 101, 283 (1945). 



