120 THE PRINCIPLES Otf AGRICULTURE. 



oxygen when separated from the carbon would form 

 water. 



They are either oxidized in the body to produce heat 

 and energy, or are converted into fat. They are the 

 least valuable of the digestible parts of food. Starch 

 is an important part of these substances, and about two 

 and one half parts of starch are required to produce the 

 same effect as one part of fat. 



5. Fiber. Most kinds of food contain more or less 

 crude woody fiber, which is mostly indigestible and 

 hence has little value as food. 



6. Ash. The mineral substances in food, or those 

 which would remain as ashes after burning, are also 

 needed by the animal in about the same proportion as 

 they exist in the average -of the different varieties of food. 

 When animals are confined to one particular kind of food, 

 some of these substances may be deficient. Although 

 the amount required is small, they cannot be dispensed 

 with. Animals fed exclusively upon corn meal some- 

 times lose the use of their legs from the want of sufficient 

 mineral matter to form bones. 



On the page opposite is a table of some of the more 

 common foods, with their average percentage composi- 

 tion, as determined by chemical analysis. 



While the list gives the average results from a large 

 number of separate tests, and must be approximately 

 correct, it should be remembered that different samples 

 differ widely in their nature. 



There would be a wide difference, for instance, be- 

 tween the composition of early and late cut hay, or 

 between unripe and mature corn fodder. 



While these figures may not accurately represent 

 the composition of any particular sample of food, they 



