ENERGY VALUES FOR COMPUTING RATIONS 95 



Waste of Chemical Energy. Not all the energy 

 contained in a feeding stuff or ration is utilized. A 

 certain quantity is never digested, but is excreted as 

 dung. Another loss of chemical energy arises from 

 combustible gases due to fermentation of feed in 

 the digestive tract. Still another source of lost 

 energy is material passing out of the system in urine. 

 Armsby states that 22 per cent of the chemical en- 

 ergy of corn meal and 55 per cent of that of average 

 hay has been found to escape in these ways. 



But one of the most important causes of energy 

 loss is that occasioned by the processes of digestion, 

 in which the energy that is utilized for fattening 

 increase or other productive uses must be separated 

 from the consumed material. 



All of these factors enter into the digestive prob- 

 lem and consume much of the contained nutrients 

 for other functions than those of tissue or fat in- 

 crease, or fuel, or energy. 



Energy Values in Feeds. Feeding stuffs possess 

 both a maximum amount of chemical energy and a 

 certain quantity of net energy. The former refers to 

 the theoretical quantity, and the latter to that which 

 is actually available for productive uses. It is with 

 the net energy that the feeder has to deal in the 

 preparation of his rations. From tests made by 

 means of the respiration calorimeter much definite 

 knowledge has been obtained, so as to permit ap- 

 proximate estimates showing the net energy in con- 

 nection with the total dry matter and digestible pro- 

 tein. This is shown ir the following table : 



