246 THE PRINCIPLES OP AGRICULTURE 



amounts of protein are mainly found in the grains 

 and other concentrated foods that are relatively 

 high-priced. Both these conditions make the 

 problem of successful feeding largely one of the 

 sufficient and economical supply of albuminoids. 

 If an insufficient amount is furnished, the animal 

 suffers in growth or production: if more than 

 enough is supplied, costly waste ensues. 



Ze. Carholiijd rates 



445. By far the largest part of the dry matter 

 of fodders is classed with the carbohydrates, the 

 most familiar examples of which are sugars, 

 starch, gum and vegetable fiber (371). These 

 substances contain carbon, oxygen, hydrogen — the 

 two latter in the proportions in which they are 

 found in water. They contain no nitrogen. 



446. By union with oxygen in the lungs and 

 blood, the carbohydrates are decomposed into 

 carbonic acid (carbon dioxid) and water, and 

 heat is evolved in precisely the same way as 

 under ordinary combustion in the air. They 

 are thus the main source of heat to the animal. 

 They are also a source of muscular energy, and 

 in most cases an important source of fat in both 

 tissue and product. 



447. Of the carbohj'drates, fiber is much less 

 readily acted on by the digestive fluids, and 

 often a large part of it passes through the animal 



