SECTION XIII. 



FEED STUFFS AS A SOUKCE OF ENERGY. 



We all know that when work is performed a certain amount 

 of effort is put forth. This effort is proportional to the work 

 done and energy is expended in the performance of the same. 

 What is true for man in this respect applies for animals. The 

 animal may be likened to the steam engine. It moves itself and 

 also is capable of moving other things. The animal differs from 

 the steam engine in that it never stops ; it is continually at work. 

 No matter how quiet the animal, the blood is pumped by the 

 heart to all parts of the body, inspiration and expiration of air 

 to and from the lungs is continuous, and the processes of diges- 

 tion are being performed, so that energy is always being ex- 

 pended by the animal. 



Sources and Uses of Energy. — In order that the animal may 

 breathe, walk, run, trot, pull a load, plow, masticate, digest food, 

 etc., it must be furnished with materials to enable it to perform 

 these functions. The source of these substances is obtained 

 from the compounds which the plant stores up as latent heat and 

 is transformed by the animal into fats and flesh. We know that 

 an animal deprived of plant substances soon wastes away. The 

 animal therefore in performing work of any kind uses the sub- 

 stances, fats and flesh. The fats are used to furnish the fuel 

 and the flesh to repair the tissues. Energy in animals is mani- 

 fested by muscular movements. It is generally derived from 

 the non-nitrogenous substances. The muscles are moved by the 

 action of the non-nitrogenous substances. Let us represent the 

 sources and uses of energy as follows: 



Food compounds Animal compounds Functions 



Carbohydrates and fats changed to Animal fats Used as fuel 



Protein, water and ash changed to Flesh, fluids and the Used as repair 



body framework materials 



Use of Compounds Fumishii^ Energy. — As previously men- 

 tioned the carbohydrates and fats comprise the fuel portion of 

 the food. Should these compounds be fed in amounts just suffi- 

 cient to do the work required, no excess will be stored in the 



