UNITED STATES DEPARTMENT OF AGRICULTURE 



BULLETIN No. 637 



Office of the Secretary 



Contribution from the Office of Farm Management 



W. J. SPILLMAN, Chief 



Washington, D. C. 



January 14, 1918 



A METHOD OF CALCULATING ECONOMICAL BAL- 

 ANCED RATIONS. 



By J. C. Rundles, Scientific Assistant. 



CONTENTS. 



New method of balancing rations 2 



How to use Tables I and II 7 



Table of equivalent prices 7 



How to use Table III 8 



Relative value of feeds 8 



Relative value of protein feeds 8 



How to use Table IV 12 



Relative value of carbohydrate feeds when the 



cheapest available feed is nitrogenous 13 



How to use Table V 16 



Howtouse Table VI 17 



Economy in feeding is of prime importance to the feeder. It in- 

 volves judgment in the selection of feeds as well as skill in the mixing 

 of rations. The feeder may know that he needs a concentrate rich 

 in carbohydrates or one rich in protein, yet be at a loss to determine 

 the cheapest form of the desired concentrate to buy. Again, he 

 may have certain feeds available and be unable to determine the 

 most economical proportion in which they should be fed to give a 

 ration of a desired nutritive ratio. This bulletin suggests ways in 

 which these problems may be solved by fixed rule as they arise. 



It is, of course, generally understood among students of nutrition 

 that protein, carbohydrate, and fat content of a feeding stuff is not 

 the only factor affecting its feed value. Proteins differ in their 

 nutritive qualities, while some substances not included in the classes 

 above mentioned are necessary to the proper maintenance of the 

 bodily functions. The palatability and succulence of a feeding stuff 

 has much to do with its value as a feed. Many feeding stuffs have 

 physiological effects entirely apart from their nutritive qualities. 

 Again, a ration may be perfectly balanced from the standpoint of 

 relative content of protein and energy producers, and yet be quite 

 impracticable because too bulky or too concentrated. It is there- 

 fore understood that any consideration of a feeding stuff or a ration 



18026°— 18— Bull. 637 1 



