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The Cornell Reading-Courses 



Water. — The use of the water in the food has already been 

 indicated. 



Ash. — The ash required by the animal does not need to be computed 

 carefully because all the ordinary foods furnish it in sufficient amount, 

 provided a good variety is given and plenty of salt is supplied. Corn 

 is slightly deficient in ash, but in the ordinary ration the foods fed with 

 corn make up for this deficiency. 



Protein. — The protein, carbohydrates, and fats in food are commonly 

 spoken of as the nutrients of the dry matter, since it is from those groups 



Fig. 3. — Another use of the energy and matter in food, stored in the body as flesh and 



fat for the future use of man 



of constituents that animals derive the matter and energy necessary for 

 the uses already enumerated. The protein is used to keep up the protein 

 of the body — that is, to replace worn-out tissues, to build up new tissues, 

 for growth of hair, hoofs, horns, and the like. A very important fact 

 in this connection is that any protein in the ration in excess of that re- 

 quired for keeping up the nitrogenous tissues of the body can be used 

 by any animal for the production of heat and energy. On the other 

 hand, while protein can be used thus for the production of heat 

 and energy, thus serving the purpose of carbohydrates and fat, 

 protein cannot be produced from the carbohydrates or the fats of 

 foods. Therefore it is always necessary to have a sufficient amount 



