DIGESTION AND NUTRITION 327 



digestible protein, equivalent to 64 per cent, of the total. 

 (2.16 -r- 3.36 X ioo = 64). 64 is the digestion coeffi- 

 cient of the crude protein in this clover hay. In like 

 manner, the digestion coefficients of all of the nutrients 

 are determined. 



Example. From the following figures, calculate the digestion 

 coefficients of the organic matter, ether extract, crude fiber and 

 nitrogen -free extract of the clover hay. The figures for the com- 

 position of clover hay are on the basis of the food as fed, while 

 those for the feces are on the basis of the dry matter. 



Composition of clover. Composition of feces 

 Hay as fed. (Dry matter.) 



Water 10.00 .... 



Ash 6.90 9.50 



Ether extract 3.10 2.10 



Crude protein 12.00 I5r 



Crude fiber 26.00 30.00 



Nitrogen-free extract 42.00 4340 



451. Caloric Value of Foods. During the process of 

 digestion, heat is produced in proportion to the calories 

 contained in the food and the nutrients digested. By 

 the caloric value of a food is meant the amount of heat 

 measured in calories which the food yields. A calorie is 

 the amount of heat required to raise i kilogram of water 

 i C. or i pound of water about 4 F. The caloric 

 value of a food is determined by means of the calorimeter 

 (Fig. 94). The calorimeter consists of a steel bomb 

 that is placed in a metal cylinder (Q) (Fig. 95). The 

 bomb is surrounded by water as indicated in the illus- 

 tration, and the cylinder containing the bomb and water 

 is placed within a double-walled fiber receptacle ( T 

 and U). The bomb itself consists of three parts : The 



