X.] 



HEAT VALUE OF FEEDING STUFFS 



189 



mixed feeding stuff in terms of starch. For example, 

 100 lb. of meadow hay (Table XVII.) contains : — 



Thus, 100 lb. of meadow hay are equivalent to 48-4 lb. 

 of starch by calculation from the constituents, whereas 

 Kellner found by experiment, as shown above, that when 

 I of starch gave 37 calories, i of meadow hay gave 

 1-8 calories, or 100 of meadow hay give as much heat as 



- — ^^^^ = 487 of starch, a sufficiently close agreement. 



If the animal is at rest, either fattening or on a mere 

 maintenance diet {i.e. the minimum diet which will 

 keep it stationary in weight), then the whole of the heat 

 values of the foods expressed in the last column, less 

 what is stored as fat and flesh, will be developed in the 

 animal's body, and will go to keep it warm. If, however, 

 the animal is at work, then the amount of energy thus 

 developed will not appear as heat inside the animal. It 

 is, of course, true that even when at rest in the stall the 

 animal is doing a certain amount of internal work, but 

 this internal work being done inside the body is there 

 reconverted into heat without loss ; it is only work 

 outside the body, as in drawing a cart or turning a mill, 

 that is lost as animal heat, because it is converted into 

 some other form of energy that can be stored outside 

 the body. But as regards the internal work of the 



