CHAPTER IV 



MAINTAINING FARM ANIMALS 



I. Requirements for Body Fuel 



Farm animals are given food in order that they may convert it 

 into useful products, like meat, milk, wool, and work. Just as a 

 factory must be supplied with power to keep the machinery in motion 

 before any product can be turned out, to make continued production 

 possible with the animal enough food must first be provided to main- 

 tain all necessary life processes. This amount of food, which is 

 required merely to support the animal when doing no work and yield- 

 ing no material product, is called the maintenance ration. When an 

 animal is receiving a maintenance ration its body will neither gain 

 nor lose protein, fat, or mineral matter. 



On the average, fully one-half of the feed consumed by farm ani- 

 mals is used simply for maintenance, only the remaining half being 

 turned into useful products. Thus, it is just as important to under- 

 stand the principles governing the maintenance requirements of farm 

 animals as those controlling the production of meat, milk, or work. 



To maintain an animal at rest without losing or gaining in weight, 

 sufificient food must be supplied to furnish: (1) Fuel to maintain 

 the body temperature; (2) energy to carry on such vital functions as 

 the work of the heart, lungs, etc.; (3) protein to repair the small 

 daily waste of nitrogenous tissues; (4) mineral matter to replace the 

 small but continuous loss of these materials. 



Maintaining the body temperature. — The body temperature of the 

 larger farm animals ranges from 98.4° to 105.8° F. To keep the 

 body at these high temperatures, heat must be continuously produced 

 within it. We have seen that, especially with ruminants, much heat 

 is generated in the digestive tract by the breaking down of cellulose 

 and other plant compounds. The remainder is produced in the tissues 

 of the body in the following manner: Thru breathing, the oxygen 

 of the air is brought to the blood. Floating in the blood stream, are 

 myriads of microscopic bodies called red blood corpuscles, which owe 

 their color to hemoglobin, an iron-containing protein. This hemo- 

 globin absorbs the oxygen and holds it loosely. As the blood, now 

 laden with oxygen, passes thru the capillary system, it gives up the 

 oxygen to the living body cells. Here, in some marvellous manner 



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