292 Nature-Study Agriculture 



Oil and tains protein, but any food may assist in forming fat. 



2rafe ty ~ The chief fattening foods are oil and carbohydrates. 

 (Sugar and starch are examples of carbohydrates.) 

 Corn is used to fatten cattle because it contains large 

 quantities of both oil and starch. There are five pounds 

 of oil and seventy pounds of starch to each hundred 

 pounds of corn. (Exp. 2.) 



Oil as a Oil (or fat) may be considered as a sort of concentrated 



carbohydrate. It serves much the same purpose in 

 food as sugar and starch; namely, to produce energy 

 and animal heat. Oil is made of carbon and hydrogen, 

 the elements that starch and sugar are made of; but 

 it contains these elements in a different proportion, with 

 the result that oil is more than twice as heating as either 

 starch or sugar. 



Feeding The proper amount of feed. The agricultural experi- 



ment stations of the United States government have made 

 tests to determine the values of different kinds of feed in 

 different amounts, and they have kept careful records 

 of the results. Thousands of feeding tests have been 

 made in other countries as well, and a great deal has 

 been learned from them. 



The feed It has been shown by such tests that a horse weigh- 



andof cows m g one thousand pounds needs about twenty pounds 

 of feed a day, and that a cow of the same weight needs 

 twenty-five pounds. Only the dry matter in the hay, 

 after all moisture has been evaporated, is represented 

 in these weights. The horse's stomach is smaller than 

 that of the cow and it is differently constructed, so that 

 the horse cannot eat so much. The horse, however, 

 needs about as much nutriment as the cow ; so its feed 



