X.] ENERGY AVAILABLE FOR WORK 193 



Deductions must now be made for the undigested 

 part of the food, for the urea and the methane excreted, 

 as follows : — 



Undigested Oil, 0-5 grammes at 9-2 cals. . = 4*6 

 Undigested Protein, 7 grammes at 5-8 cals. . = 40-6 

 Undigested Fibre, 14 grammes at 4-1 cals. = 57-4 



Urea from 34 grammes digested protein at 



I- 1 calories . . . . . = 37*4 



Methane from 20 grammes digested carbo- 

 hydrates, etc., at 0-4 calories . . = 8-o 



148-0 



Deducting these 148 calories from the fuel value, 

 460 calories, we get 312 calories as the heat value of the 

 cotton cake. We have now to make a further deduc- 

 tion of 3 per cent, (or 9 calories) as the internal work 

 spent in digestion, leaving 303 calories as the dynamic 

 energy of 100 grammes of decorticated cotton cake avail- 

 able for transformation into work or storage as fat in the 

 animal ; though, as will be seen later, only a certain frac- 

 tion of this can be so converted or stored. 



Let us now compare meadow hay, calculating on the 

 same lines : — 



2-5 grammes fat at 8*2 calories . . = 20*5 



10 grammes protein at 5-8 calories . . = 58-0 



68 grammes carbohydrates and fibre at 4-1 cals. = 278-8 



Calories, fuel value 357*3 



Deductions : — 



Undigested Fat, 1-5 grammes at 8-2 calories . = 12*3 

 Undigested Protein, 6 grammes at 5-8 cals. . = 34-8 

 Undigested Fibre, 27 grammes at 4-1 cals. . = 110-7 

 Urea from 4 grammes digested protein, at 



I- 1 calories . . . . = 4-4 



Methane from 41 grammes digested carbo- 

 hydrates, etc., at 0-4 calories . . = 16-4 



178-6 



N 



