FEEDS AND FEEDING 381 



Three Great Classes. --The part of the food that 

 is consumed by burning is the part called organic 

 matter. The organic components of feeding stuffs fall 

 into three classes, Proteins, Carbohydrates, and Fats. 



The chief consideration in feeding is to obtain, in 

 the correct proportions and with the greatest economy, 

 a supply of each of these classes of foods adequate to 

 build up the body and to furnish the animal products 

 desired. 



Note. Dry hay contains from 10 per cent to 20 per cent of water. 

 The grains contain about 10 per cent and silage contains as high as 80 

 per cent of water. 



Protein. --The chief function of the protein in food 

 is to form lean tissue. It also is one of the most im- 

 portant parts of milk and of eggs. Protein contains 

 other elements (see page 26), but the most important is 

 nitrogen ; on this account the protein part of food is 

 called nitrogenous. This is the most expensive con- 

 stituent of feeding stuffs. Foods for stock containing 

 a large proportion of digestible protein are sold on the 

 market at a relatively higher price than any others. 



Carbohydrates. --The chief functions of carbohy- 

 drates are to furnish energy and to form fat. The 

 largest part of the dry matter of most foods as eaten 

 is carbohydrates. It is the cheapest part of food for 

 animals. There are two classes of carbohydrates found 

 in pi ants; namely, fiber and nitrogen-free extract. The 

 fiber is the hard woody framework of the plant and 

 the coarser bran of grains. It is of very little food 

 value because of its nondigestibility. Nitrogen-free ex- 

 tract includes the more easily digested carbohydrates, 

 the starches, sugars, and gums. It is called nitrogen- 



