NET ENERGY VALUES AND STARCH VALUES. 



By henry PRENTISS ARMSBY and J. AUGUST FRIES. 



Inslitiilt' of Aniiiial Nulritmi, Stale College, Pennsylvania. 



It is now accepted as a fundamental doctrine in animal nutrition that 

 the prime function of food is to supply energy for the operation of the 

 human or animal body and that all its other diverse uses are essentially 

 tributary to this main purpose. The growing recognition of this fact 

 in its relations to the nutrition of farm animals has given rise during 

 the past twenty-five years to extensive investigations, especially by 

 Zuntz and his associates, by Kellner and Kohler and by the writers, in 

 which the attempt has been made to determine experimentally how 

 much energy the various feeding stuffs can actually contribute toward 

 the upkeep of the animal body. 



Zuntz's investigations have been chiefly upon the horse and will 

 not be discussed here. Kellner's and our own have been upon cattle. 

 For them the same general methods have, in the main, been used and 

 the results have been in general accord. In the actual application of 

 those results to practice, however, two quite diverse, although not 

 fundamentally inconsistent, methods have been followed, with more or 

 less resulting confusion. The matter has seemed to us to be of sufficient 

 importance to warrant a brief contribution to the discussion of the 

 subject and an attempt to make clear what we, at least, conceive to be 

 the relation between the two systems. 



The earlier of the two was Kellner's system of "Starch values," 

 which before the war had obtained wide currency not only in Germany 

 but in other countries of continental Europe and to some extent in 

 Great Britain. 



Kellner's starch values are in reality disguised energy values. In 

 his fundamental investigations he used substantially the same general 

 methods adopted subsequently by the writers; that is, he determined 

 by so-called indirect calorimetry, using a Pettenkofer respiration ap- 

 paratus, what part of the total energy contained in a variety of feeding 

 stuffs could actually be recovered as gain of flesh and fat by the animal. 



