96 



PRINCIPLES OF FEEDING FARM ANIMALS 



of combustion of coal placed under the boilers of a steam 

 engine. Thus one ma}- compare the losses of energy in the 

 animal body to the unburned or only partially burned soot, 

 smoke, and cinders of the coal. The energ>^ of the coal 

 which actually is liberated under the boiler of the engine 



Fig. 22. — Respiration culorinicter at the Institute of Animal Nutrition, 

 State College, Pa. 



corresponds to the metabolizable or available energy of the 

 feed. 



The metabolizable energy of a feedingstuff is determined 

 by means of the ])omb calorimeter already mentioned, and 

 an apparatus known as the respiration calorirneter. The 

 respiration calorimeter is a very complicated apparatus, by 

 means of wliich the amounts of gas, urine, feces, and heat 



