352 



CORN 



similate its food ; to transform the crude food products into milk prod- 

 ucts or eggs ; or, as in the horse to do its daily work. They also furnish 

 heat to the body. After these maintenance requirements are fulfilled 

 whatever food elements are left are stored away in various parts of 

 the body in the form of animal fat for further use. 



Then when food supplies are insufficient, the animal draws upon 

 its body fat for material out of which to manufacture milk, 

 or for fuel to keep its body warm. The fats or oils of grains and fod- 

 ders act in the body in very much the same way as do the carbohy- 

 drates, but they produce a greater amount of heat and energy. Fat 

 has about 2.4 times as much heat and energy producing power as 

 have the carbohydrates. For this reason, fats rank .next in impor- 

 tance after protein as an essential part of an animal's ration. Protein, 

 the fats, and the carbohydrates, are the three important food materials, 

 but since the fats meet the same fate in the body as do the carbo- 

 hyarates, there are really only two chief substances, (i) the flesh form- 

 ers (protein) ; and (2) the heat and energy formers (carbohydrates and 

 fats). The part that each of these three constituents plays in the ani- 

 mal economy, is indicated in the following diagram : 



I FEED sVufT 



rieih.wool etc. . 



MilU jolids. egg olbummi 



Meat ond energy 



Hear and energy 



Body fot. 

 Butter-fat etc. 

 heot ond enerqy. 



Crude Fiber. The cells and frame work of growing plants as well 

 as the covering of seeds and grains are made up of more or less woody 

 fiber called "cellulose." Cellulose is chemically similar to the starches 

 and therefore might properly be termed a carbohydrate, but as the 

 greater portion of it is practically indigestible, this indigestible or 

 insoluble portion is classed by itself as "crude fiber." While yielding 

 very little matter nutritious to the feeding animal, crude fiber has 

 an important mechanical eflfect on the digestion of food. 



It is the crude fiber in the feed that gives bulk to the contents of 

 the paunch, and unless a cow or steer receives sufficient "roughage" 

 with its ration it cannot ruminate. There is no foundation for the 



*An originftl diagram, designed by Prof. L. G. Michael of the Iowa Experiment Station. 



