12 



FEEDING VALUE OF CEREALS. 



metabolizable energy. The last is calculated both according to the 

 figures of Ke liner and of Riibner, for the purpose of comparison: 



TABLE V. Metabolizable energy. 

 [ Pounds per hundred pounds.] 



As before stated, the metabolizable energy of a food is the total 

 amount of energy which an animal is able to derive from that portion 

 of food that is digested and actually used by it after allowing for all 

 waste. This was originally termed the available energy of the food 

 and w r as considered to be a measure of the value of the food. There 

 are, however, still other factors entering into the problem that need 

 to be considered which make it necessary to distinguish between this 

 available or metabolizable energy and the,, net available energy of 

 the food. 



The animal body has been likened by Armsby to a steam boiler fed 

 by means of a mechanical stoker, the power for operating which 

 conies from the steam generated in the boiler itself. The available 

 energy of the coal for producing steam power is equivalent to the 

 fuel value of the coal less that of the refuse and again diminished by 

 the amount of energy used in operating the mechanical stoker. 

 Similar conditions obtain in the animal body. In order to get the 

 food and chew and digest it, a certain amount of the animal energy 



