288 Effective Farming 



required by different classes of animals, whether or not the feeds 

 are palatable to the animals, and their cost and availability. 



156. Functions of feed. When taken into the animal body 

 and digested and absorbed, feed performs certain functions. 

 In the first place it creates energy that is used in moving the 

 body about, in heating the body, in carrying blood through the 

 circulatory system, in moving the food through the alimentary 

 canal, and the like. In addition, energy is required to produce 

 the changes that are going on in the cells of the body. The 

 feed also builds up the tissues of the body and secretes the 

 fluids necessary for the life processes. Tissues are constantly 

 wearing out and must be replaced. 



The water, ash, carbohydrates, protein, and fat all have their 

 uses when taken into the animal body. Water is contained 

 in every kind of living tissue and none of the life processes 

 can be carried on without it. The body of an animal is about 

 50 per cent water and the fluids range from 90 to 99 per cent 

 water. As in plants, water is the means by which the food 

 is carried from place to place in the body. Water also helps 

 to keep the temperature normal. 



Ash is used largely to furnish mineral matter for the bones. 

 In the case of hens it furnishes the material for the egg-shells. 

 A certain amount of ash is found in all tissue. 



fe 



Lean meat, or muscle, blood, skin, hair, hoofs, and vital 

 organs are largely protein. As these tissues are made out of 

 the protein of the feed, it is readily seen why the proper quan- 

 tity of protein in the feed is so necessary. If there is in the 

 feed more than enough protein to supply that needed in build- 

 ing up the lean meat and other tissues, the surplus goes to 

 make energy. As energy can be produced more cheaply by 

 the use of carbohydrates and fats, it is not profitable to have 

 feeds contain a larger proportion of protein than is necessary. 



The carbohydrates produce energy and heat and build up 

 the fat of the body. Therefore, feeds rich in carbohydrates, 

 such as corn, are fattening. 



