542 Report of the Departmeint of Animal Btisbanury of thb 



THE RELATIVE NUTRITIVE EFFECT OF RATIONS FROM 

 UNLIKE SOURCES. 



The main reason why a unit of digestible material from unlike 

 sources may not have a fixed food value has already been dis- 

 cussed, viz.: the great variations in the character of the protein 

 and nitrogen-free extract. For instance, in the grains, the nitro- 

 gen is almost wholly albuminoid, and the nitrogen-free extract is 

 largely starch, while in coarse fodders and roots, much of the 

 nitrogen may come from amid compounds and the nitrogen-free 

 extract contains a generous proportion of pentosans and other 

 bodies not so well understood. Even among the grain foods 

 there are important differences of this kind. Certain of the com- 

 mercial feeds are residues of the manufacture of beer, glucose 

 and starch from the cereal grains, the starch of the barley and 

 corn having been largely extracted. This results in a concentra- 

 tion of the nitrogen compounds as a whole, and of the nitrogen 

 free compounds that are not starch or sugars. May these un- 

 doubted differences have an appreciable influence upon the nutri 

 tive effect of two rations? 



The two rations under discussion in this connection were 

 selected for a feeding experiment because they illustrate the 

 facts we are now considering. We have shown that they con- 

 tain practically the same amounts of digestible material with 

 very nearly the same nutritive ratio. The actual compounds in 

 the two rations are in part quite unlike, however. It is well 

 to call attention, in this connection, to the fact that the hexose 

 sugars and the starches as found in cattle foods possess certain 

 characteristics that distinguish them from any other of the com- 

 pounds which make up the nitrogen-free extract. The sugars 

 either require no changes through digestion in order to be di- 

 rectly absorbed into the circulation, or only a change from one 

 sugar to another, while starch, through the action of diastatio 

 ferments easily suffers complete hydrolysis to one form of sugar. 

 In other words, these carbohydrates are readily and wholly 



