336 



VETERINAKY PHYSIOLOGY 



stances is generally greater in the young than in the older 

 parts of plants. Thus in quite young grass about 70 per cent, 

 of the nitrogen is in proteins, and about 30 per cent, not in 

 proteins ; while in old grass about 80 per cent, of the nitrogen 

 exists in proteins. Again, in extracting fats witli ether, 

 chlorophyll, the green colouring substance of plants and other 

 matters are removed along with the fat. Hence it must be 

 remembered that the proteins and fats in the following table 

 are somewhat too high : 



Average Percentage Composition. 



The soluble carbohydrates are determined by taking the 

 difference between the total solids and the proteins, fats, and 

 insoluble fibre combined. But while a rough measure of their 

 amount is thus procured, the presence of various gummy sub- 

 stances may somewhat vitiate the results. 



For these reasons no attempt is made in the table above 

 to give more than rough approximate results of analysis such 

 as will be found useful in regulating the diet of domestic 

 animals. 



Cooking of food for animals has two purposes First, to 

 soften and burst the cell capsule of vegetable foods so as to 

 render the contents more readily available; and second, to 

 destroy bacteria. 



