ILLINOIS DAIRYMEN'S ASSOCIATION. 317 



The principal uses of protein in the body of the cow are to 

 build muscles, replace their waste, and form casein in milk. There 

 are two reasons why special attention should be given to the 

 amount of protein contained in the different feeds : first, because 

 it is usually deficient in feeds for dairy cows ; second, because no 

 other nutriment answers the same purpose. 



Carbohydrates. 



Carbohydrates is the name applied to the carbonaceous group 

 of substances such as starch, sugar, and the woody parts of plants 

 known as crude fiber. This group forms the larger part of the 

 food consumed by animals, as we shall see later. Carbohydrates 

 furnish energy to perform the body functions and for the muscu- 

 lar activity. The heat of the body is the result of energy expended. 

 It takes a large amount of energy to build up a product like milk 

 If carbohydrates are fed in excess of the demands for energy, fat 

 may be stored up in the body. In case of the dairy cow, carbo- 

 hydrates, besides supplying the above requirements, furnish the 

 constituents for forming milk sugar and fat in milk. 



Fat. 



Every one is familiar with fat in its different forms ; as tal- 

 low in the steer, lard in the hog, and butter fat in milk. In corn 

 there is about 4.3 per cent of fat, or oil, and in flaxseed a much 

 larger proportion, while in most of the rough fodders there is 

 comparitively little. Fat in the food nourishes the body in ex- 

 actly the same way as do carbohydrates : namely, furnishes energy 

 and forms fat. The chief difference between fat and carbohy- 

 drates is that the former is a more concentrated form of food, one 

 pound bfing equal to 2.4 pounds of carbohydrates. It should be 

 remebered that fat and carbohydrates are interchangeable, that 

 is, whichever one is in excess may take the place of the other.but it: 

 must also be borne in mind that however great the excess of car- 

 bohydrates and fat in the ration, no more muscle can be formed 

 in the body, or casein produced in the milk than there is protein 

 in the food supplied. In other words, where protein is in ex- 

 cess it can take the place of carbohydrates and fat, but no amount 



