36 PRINCIPLES OF FEEDING FARM ANIMALS 



Uses of Feed. It has been shown that the digested and assimi- 

 lated feed is oxidized in the cells and tissues of the body; the 

 chemical energy thus set free is utilized in one or more of three 

 different ways : As kinetic energy, for the maintenance of the body 

 heat, or as mechanical energy, for the production of internal work 

 in the body of the animal or for mechanical labor (horses, mules, 

 and oxen), or as chemical energy stored in the form of animal 

 products. If the energy supplied in the feed is more than sufficient 

 to cover the demands for the first two purposes given, the excess 

 may be stored up in the body in the form of animal products, like 

 meat, fat, milk, eggs, etc., which may later serve to supply energy 

 to man or other animals when used in their feed. 



The functions of the different components of feed are, briefly 

 stated, as follows : 



Protein. Flesh-forming substances. Essential for the produc- 

 tion of lean meat, muscles, skin, ligaments, horns, hair, wool, milk, 

 etc. When present in excess in the feed, used for production of body 

 fat or as fuel, to give warmth and energy. Of general value in 

 stimulating nutritive processes in the body. 



Fats. Furnish fuel to keep the animal warm and produce 

 energy. Aid in the production of fatty tissue. For the produc- 

 tion of heat, 2.25 times as valuable as carbohydrates. 



Carbohydrates. Supply fuel to keep the animal warm and 

 produce energy for muscular work. They are transformed into 

 fats for the production of fatty tissue. 3 



Feed for Production. The portion of the ration fed an animal 

 over and above maintenance requirements is the productive part 

 of the ration; the higher this can be increased up to the capacity 

 of the animal for digestion and absorption of feed, the better are 

 the returns obtained and the more economical is the production, 

 so far as feed consumption is concerned. The amounts of nutrients 

 required by the different farm animals for productive purposes have 

 been determined in similar ways as in the case of the maintenance 

 standards. The first attempts to formulate general standards for 

 farm animals were made by the German scientist Grouven in 1858. 

 He gave the quantities of total dry substance, protein, and fat 

 which an animal of a certain age would require daily in its feed 

 ration. A somewhat later effort in this direction is represented by 

 the standards proposed by Wolff, in which the amounts of digestible 

 components required by different classes of farm animals under* 

 varying conditions are given. 

 " 'North Carolina Bulletin 106. 



