324 



THE ESSENTIALS OF AGRICULTURE 



418. Improved and poor animals compared. Different breeds 

 of the same species and different individuals of the same breed 

 appear to have approximately equal digestive power. It is a 

 common notion that the improved breeds of farm animals digest 

 their food more completely than do the unimproved kinds. It 

 is true that the improved strains are capable of digesting larger 

 quantities of food within a given time, but there is no reason to 



small 

 intestines 



roof of mouth 

 tongue \ 

 pharynx-^ 



esophagus * aUvary 

 omasum, or ducts 

 'manyplies 



reticulum, or honeycomb 



abomasum, or 



rennet ( true stomach) 



colon, or large 

 intestine'"/] 



FIG. 162. The digestive tract of a cow. (Diagram from Iowa State College) 



believe that they digest their food or secure nourishment from 

 it any more completely than do the unimproved sorts. 



419. Digestibility of feeds. Some foodstuffs are more easily 

 digested than others. Milk, for example, is easily digested. 

 Grains and other foods like bran and linseed meal are compara- 

 tively easily digested. Coarse, woody fodders, like corn stover 

 or wheat straw, are digested very incompletely and with great 

 difficulty. Indeed, in masticating and digesting some very poor 

 materials more energy is required than the materials yield when 

 digested. Therefore the more of such material an animal is 

 forced to consume, the less it is nourished. 



