USES OF FEED BY ANIMALS 



35 



feed components and feeding stuffs supply is generally taken to 

 represent their value for feeding purposes, as will be shown pres- 

 ently (p. 44). This has come largely through the studies of Stoh- 

 mann, Kubner, and Kellner in Germany, and Armsby in this 

 country. 



The maintenance rations for different animals per thousand 

 pounds or one hundred pounds body weight formulated by Armsby 

 are as follows i 1 



Armsby Standard Maintenance Rations 



* Illinois Bulletin 163. The amount of digestible protein is crude, and not true protein 

 (p. ID- 



The figures given for the amounts of digestible protein and 

 energy values for maintaining swine at an even weight are derived 

 from recent investigations by Professor Wm. Dietrich, formerly of 

 the Illinois Experiment Station. 



There are a number of factors that influence the maintenance 

 requirements of animals; among these may be mentioned: The 

 muscular activity of the animals (whether standing or lying), 

 temperament, external conditions tending to affect the degree of 

 muscular activity, condition or amount of fat tissue carried, and 

 external temperatures. 2 It is believed, however, that the feeding 

 standards show with a considerable degree of accuracy the average 

 amounts of digestible true protein and energy values required by 

 the different classes of farm animals given for the maintenance of 

 an even body weight. 



It is generally assumed that the maintenance requirements of animals 

 are proportional to their live weights; i.e., a cow weighing 1200 pounds will 

 require 50 per cent more feed for the maintenance of her body weight than 

 an 800-pound cow. This is not correct, however, although sufficiently so for 

 most practical purposes. The maintenance requirements increase with the 

 surface of the animal, and this is approximately proportional to the squares 

 of the cube-roots of the weights of similar animals. If a cow weighing 800 

 pounds requires, say, 8 pounds of digestible nutrients for maintenance, a 

 1200-pound cow would require 8 X V'(^) 2 or 10.48 pounds, and a 1600-pound 

 cow, 12.7 pounds. 



farmers' Bulletin 346. 



2 Pennsylvania Bulletin 111. 



