THE PRODUCTION VALUES OF FEEDING STUFFS 659 



Williams, Riche and Lusk report results agreeing substantially 

 with those of Rubner when computed in the same way, although 

 they regard his method of computation as erroneous. Rubner's 

 and Lusk's averages are contained in the following table. It 

 should be clearly understood that these figures are not applicable 

 to the " digestible nutrients " of the feed of herbivora. 



TABLE 201. PERCENTAGE OF METABOLIZABLE ENERGY AVAILABLE 

 Average Results for Dogs 



Net energy values 



In the previous paragraphs there have been considered the 

 losses of energy in the excreta and those due to the increased 

 heat production which results from the consumption of feed. 

 As pointed out in the introductory paragraphs of this section, 

 that portion of the gross energy of a feeding stuff which re- 

 mains after deducting these two classes of losses constitutes its 

 net energy value, or its production value as regards energy. 

 Stated in a slightly different way, the net energy value is equal 

 to the metabolizable energy minus the increment of heat pro- 

 duction. It differs from the relative value, based on the di- 

 gestible nutrients or the metabolizable energy, in taking ac- 

 count of all the losses of energy to which the feed is subject. 



760. Net energy values for cattle. It is apparent from the 

 foregoing discussions that the data regarding losses of energy 

 and net energy values are much more abundant for cattle 

 than for any other species of farm animals. Combining the 



