278 The Feeding of Animals 



protein content, and they divide the price \>y the 

 ponnds of protein in a ton in order to determine the 

 rehxtive econom}" of purchasing this or that material, 

 and the feeding stuff in which the protein cost is the 

 least when so reckoned is regarded as the economical 

 one to purchase. This method seems to be absurd, for 

 it is an assumption that the nutritive value of the 

 carbohydrates and fat in commercial foods may be 

 ignored. The argument is that the farm furnishes 

 carbohydrates in abundance, and that commercial 

 products should merelj- serve the purpose of rein- 

 forcing the protein supply. If the cai-bohydrates of 

 the farm have no selling value then this argument 

 has some force, but this is ordinarily not the case. 

 When starch and similar compounds must be pur- 

 chased as a necessary accompaniment of protein, thus 

 causing a surplus of carbohj^drate food, certainly hay, 

 oats, corn, barley, or some other home product mny be 

 sold to relieve this surplus. 



Many practical feeding experiments have been con- 

 ducted for the purpose of comparing the different 

 grain products as foods for the various classes of 

 animals. Useful facts have been reached in this way, 

 especially as the greater adaptability of some materials 

 than others for a particular species. But experiments of 

 this kind cannot be relied upon to fix relative values of 

 feeding stuffs for milk production, beef production orfoi-' 

 any other purpose. This is so, first of all, because the 

 errors of such tests are so large that we cannot re- 

 gard their apparent outcome as establishing constants. 

 Again, the problems involved are too complex and the 



