THE PRODUCTION VALUES OF FEEDING STUFFS 68l 



Appendix. This should be done, however, with a distinct 

 consciousness of the inadequacy of the method and with the 

 hope that it may ultimately be replaced by one having a more 

 scientific basis. 



Meanwhile, notice should be taken of the results of several 

 recent investigations upon the mixed proteins of a few feeding 

 stuffs, particularly those of the cereal grains. 



783. Low value of maize proteins. The demonstration of 

 the insufficiency of the zein of maize for either maintenance 

 or growth (781) has tended not unnaturally to produce the 

 impression that this important feeding stuff is relatively 

 valueless as a source of .protein. Zein, however, is not the only 

 protein of maize. According to Osborne and Mendel 1 the mixed 

 proteins of maize are made up approximately as follows : 



Zein 41 % 



Maize glutelin 31 % 



Globulins, albumins and proteoses 22% 



Insoluble in alkali 6 % 



100% 



Glutelin yields all the amino acids which zein lacks and 

 the same is probably true of the other proteins of maize. Evi- 

 dently the results of experiments on zein do not show maize 

 to be valueless as a source of protein, although they do indicate 

 a relatively low value and this conclusion has been confirmed by 

 the experiments of Osborne and Mendel on rats and of Waters 

 on pigs. On the other hand, however, Hart and McCollum 2 

 were able to obtain a normal growth of pigs on rations supply- 

 ing only maize protein but supplemented by salts. 



Osborne and Mendel l have investigated the nutritive value of the 

 mixture of proteins contained in the "corn gluten" produced in the 

 manufacture of starch from maize and consisting chiefly of zein and 

 glutelin in the proportion of approximately 100 to 44. In such a 

 mixture, the deficiencies of the zein are to a greater or less extent 

 compensated for by. the glutelin, and the mixed proteins not only 

 proved adequate for maintenance but were able to support rather 

 slow growth. The addition to them of lactalbumin or of casein, 

 however, rendered them much more efficient and induced normal 

 growth. 



1 Jour. Biol. Chem., 18 (1914), i. 2 Ibid., 19 (1914), 373. 



