u6 THE CHEMISTRY OF CATTLE FEEDING 



different from that of the latter. The fats contain only about 

 1 1 per cent, of oxygen ; the carbohydrates contain about 50 

 per cent. There is also but little difference in the percentage 

 composition of the different kinds of protein (p. 66). They 

 all contain about 22 per cent, of oxygen, and are therefore inter- 

 mediate in this respect between the fats and carbo-hydrates. 



If the glyceride of stearic, palmitic, and oleic acids jointly 

 be taken as representing the average composition of the fats, 

 and cane sugar as representing the carbohydrates, the amount 

 of oxygen required for complete oxidation of these two classes 

 of compounds can be calculated from the formulae as follows : 



Fat ... C 55 H 104 6 + 



2496 -f- 860 = 29 

 Cane sugar . C 12 H22On + i2O 2 -> i2CO 2 + nH 2 O 



384^- 342= ri2 



For protein the calculation must be made from the per- 

 centage composition 



Carbon 32 X 53 I2 = I 4i'3 

 Hydrogen i6x 7 2 = 56 

 Sulphur 32 X 2 32= 2 



100 parts protein require 199 '3 parts of oxygen 

 less what it already contains 22*0 



177*3 

 It will be seen that for complete oxidation 



i part of fat requires 2*90 parts of oxygen 



i protein requires 177 



i carbohydrate requires 1*12 



Of the constituents absorbed from the food, the fat alone 

 surfers complete oxidation in the animal's body. The residue 

 resulting from the oxidation of protein consists mainly of 

 urea. A certain amount of methane is formed from the carbo- 

 hydrates. Both of these compounds are oxidisable, and the 

 amounts of oxygen required must be deducted from the 

 amounts previously calculated in order to find how much 



