122 AGRICUI^TURE OF MAINE. 



cob. There is not a great amount of fiber in the grain itself, 

 perhaps 1.7 per cent. 



Another constituent is what the chemist sometimes calls nitro- 

 gen-free extract. This is also called carbohydrates, although 

 fiber, too, is a carbohydrate. It makes up the bulk of the corn, 

 70.1 per cent, and is very largely starch. As you know, the chief 

 source of commercial starch is corn. The same starch is some- 

 times converted by the action of chemicals into glucose, and 

 before we had pure food laws it often used to mask as some- 

 thing else. 



In addition, we have one other component, the fat or oils. 

 You know when corn meal is put into a bag and left for a few 

 days the bag gets oily. This is due to the fact that corn con- 

 tains quite a little or about 5 per cent of fat. 



DIGESTIBILITY. 



This makes up the 100 per cent, and gives the chemical analy- 

 sis of corn. But that is only the first step in the story, as you 

 well know. The measure of the food value of any food is not 

 so much the amount of protein, fiber, nitrogen-free extract and 

 fat it contains as the amount which the animal that eats it is 

 able to get out of it. The amount of the constituents is found 

 by chemical analysis. The proportion of these materials which 

 is digestible, has been found by feeding experiments, the so- 

 called digestion experiments. The materials that interest 

 us most in the foods which we shall consider today are protein, 

 nitrogen- free extract and fat, or carbohydrates and fat. We 

 will include the fibre, which is not very digestible, as a carbohy- 

 drate. 



Now, in connection with corn, we wish to know about its 

 digestibility. In the case of the protein, perhaps on the average 

 68 per cent of the 10.5 per cent contained in the corn is digesti- 

 ble. Of the nitrogen-free extract, or carbohydrates, about 95 

 per cent of the 70.1 per cent is digestible; the animal is able to 

 get nearly all of it. Of the 5 per cent of fat, 92 per cent is 

 digestible. 



Hay tells a little different story. Take, for instance, timothy 

 hay. The protein of that is only 47 per cent digestible; the 

 fiber is something like 52 per cent digestible, the carbohydrates 

 62 per cent, and the fat 52 per cent. I have not given you the 



