UNITED STATES DEPARTMENT OF AGRICULTURE 



jflJf^&JU 



BULLETIN No. 459 



Contribution from the Bureau of Animal Industry. 



A. D. MELVIN, Chief. 



js\^^Lru 



Washington, D. C. 



December 15, 1916 



THE USE OF ENERGY VALUES IN THE COMPUTATION OF 

 RATIONS FOR FARM ANIMALS. 1 



By Henry Prentiss Armsby, Director of the Institute of Animal Nutrition of The 

 Pennsylvania State College; Expert in Animal Nutrition, Bureau of Animal Industry. 



CONTENTS. 



Page. 



General principles 1 



Components of the animal body 1 



Components of feeding stuffs 3 



The animal body as a machine 4 



Feed requirements 14 



The computation of rations 19 



General considerations 19 



Total feed required 20 



The computation of rations — Continued. 



Improvement of a ration 21 



Computing a ration from given feeding 



stuffs 22 



The choice of feeding stuffs 25 



The compounding of rations 28 



Bearing on farm management 29 



GENERAL PRINCIPLES. 



COMPONENTS OF THE ANIMAL BODY. 



THE MACHINERY OP THE BODY. 



The essential working parts of the body contain a great variety of 

 substances, but these may, for our present purpose, be grouped 

 under three heads — water, ash, and protein. The bones, consti- 

 tuting the framework of the body; the ligaments, muscles, and 

 tendons, which bind together and move the bones; the skin and 

 hair, or wool, which cover and protect the body; the internal organs 

 of circulation, respiration, digestion, excretion, and reproduction; 

 the brain and nerves — in short, the whole mechanism of the body — ■ 

 can be regarded as being composed substantially of these three 

 classes of substances. 



Water. — Rarely less than half and sometimes as much as three- 

 fourths of the weight of the live animal consists of water. The 



1 A revision of Farmers' Bulletin 346. 

 60978°— Bull. 459—16 1 



