176 PTEROYLGLUTAMIC ACID 



casei was essential for the chick. Concentrates of this factor were effective 

 at levels of 100 mg. per kilogram of diet. The "Norit eluate factor" is now 

 known to be PGA. 



Vitamin Be from liver (PGA) was first reported to be active for the chick 

 by Pfiffner et al.,^^ who found that addition of 2.5 mg. of vitamin Be per 

 kilogram of purified diet prevented anemia and permitted normal growth. 



a. Feather Growth and Pigmentation 



Pteroylglutamic acid is necessary for feather growth and pigmentation. 

 Mills et al.^^ reported that a concentrate of the "Norit eluate factor" for 

 L. casei promoted feathering, growth, and hemoglobin formation in chicks. 

 Frost et al}"^ raised black leghorn chicks on purified diets containing pure 

 forms of the water-soluble vitamins. The black breed of bird has the ad- 

 vantage that it readily shows the effect of PGA on pigmentation as well as 

 feather growth. Preliminary experiments with concentrates of PGA showed 

 that 0.400 mg. per kilogram of diet gave good feather growth and pigmen- 

 tation. It is interesting to note that chicks which received the supplement 

 for the first 2 weeks only showed normal feathering and pigmentation up 

 to 10 weeks even though they grew at a decreasing rate and finally began 

 to lose weight after 7 weeks. When pure PGA was injected at levels of 1, 

 2.5, 5, and 10 7 per day, it was found that the highest level gave normal 

 feathering and pigmentation. The growth rate, however, was not as high 

 as that produced by 10 % of brewer's yeast added to the diet. Most marked 

 depigmentation occurred at the 5-7 level, presumably because f(?ather 

 growth at the lower vitamin levels was so poor that true pigmentation was 

 difficult to observe. 



Depigmentation became most pronounced in the proximal portions after 

 the feathers were fairly well developed. The wing and tail feathers were 

 most affected but nearly all feathers showed some depigmentation. 



h. Requirements of the Chick 



The rcciuirements of this vitamin have been found to be between 0.25 

 and 2.0 mg. per kilogram of diet, depending on the criteria of adequacy. Camp- 

 bell et al.^^ noted that 0.4 mg. per kilogram of diet was sufficient for main- 

 tenance for normal hemoglobin, hematocrit, red cell count, and 

 thrombocyte values, but 4 mg. per kilogram was required for maintenance 

 of normal leu(!Ocyte levels. 



30 J. J. Pfiffner, S. B. Binkley, E. S. Bloom, R. A. lirown, O. D. Bird, A. D. Emmett, 

 A. G. Hogan, and B. L. O'Dell, Science 97, 404 (1943). 



31 R. C. Mills, G. M. Briggs, Jr., C. A. Elvehjem, and E. B. Ilarl , Pmr. Sor. Exptl. 

 Biol .Med. 49, ISO (1942). 



'2 D. V. Frost, F. V. Dnnn, and F. C. Mclntire, Pmc. Soc. K.vpH. Biol. Med. 61, 05 



(1946). 

 33 C. J. Campbell, R. A. Brown, and A. D. Emmet t, J. Biol. Chem. 152, 483 (1944). 



