156 FIRST PRINCIPLES OF AGRICULTURE. 



the amount or the per cent digested is called ^^the di- 

 gestion co-efficient." 



For example, it is found by experiments that clover 

 hay of average quality shows digestible : — 



Fat 43 per cent. 



Fibre 48 " 



Protein 49 " 



Nitrogen-free extract 58 " 



These figures represent the proportion or pounds per 

 hundred of the various constituents digested, and are used 

 in calculating the digestibility of other samples of the 

 same kind of product of average quality. They are the 

 digestion co-efficients. 



The average composition of clover hay is : — 



"Water 15.3 per cent. 



Crude Fat 3.3 



Crude Fibre 24.8 



Crude Protein 12.3 



Crude Ash 6.2 



Nitrogen-free extract 38.1 



The calculation of the digestibility of clover hay is, 

 therefore, as follows : — 



Digestible Fat . . . . 



Digestible Fibre . . . 



Digestible Protein . . 



Nitrogen-free extract . 



3.3X0.43= 1.42 per cent. 

 24.8X0.48 = 11.90 " 

 12.3X0.49= 6.03 " 

 38.1X0.58 = 22.10 " 



The digestible fibre has been found to consist of cel- 

 lulose ; hence, in stating the digestibility of a food, the 

 per cent of crude fibre digested is added to the nitrogen- 

 free extract, and the result stated as follows : — 



Fat 1.42 per cent. 



Protein 6.03 " 



Carbohydrates 34.00 " 



