FEEDING STANDARDS— CALCULATING RATIONS 93 



in the various feeds. This is given in full as Appendix Table VII of 

 this book. 



Of all the cereals listed, it is shown that wheat has the highest net en- 

 ergy value, 91.82 therms per 100 lbs. Due chiefly to the large amount 

 of fiber contained in the hulls, the net energy value of oats is only 

 67.56 therms per 100 lbs. The roughages, which are high in fiber and 

 thus require much energy in mastication and digestion, furnish much 

 less net energy than the concentrates. Wheat straw is the lowest in 

 net energy of the dry roughages listed, having a value of only 7.22 

 therms per 100 lbs. 



The Armsby feeding standards. — Armsby has drawn up feeding 

 standards, based on his net energy values, for maintaining horses, 

 cattle, and sheep, for growing cattle and sheep, for milch cows, and for 

 fattening cattle. These are given in Appendix Table VIII, together 

 with Kellner's standard for work horses, converted from starch values 

 to therms, which is recommended by Armsby. Armsby has presented 

 no standards for fattening sheep or lambs, for growing horses, or for 

 pigs. In these standards, as will be noted, the requirements of the 

 various classes of animals are expressed in terms of digestible true 

 protein and therms of net energy. 



In the AVolff-Lehmann standards it is assumed that the require- 

 ments for maintaining animals depend on the live weight, the standards 

 giving the nutrients required per 1,000 lbs. live weight. Armsby in 

 his standards recognized the fact that the maintenance requirements 

 depend not strictly on body weight but on body surface. (See Page 

 52.) He therefore gives separate figures for animals of various 

 weights. It will be noted that for maintaining a 500-lb. horse 0.6 lb. 

 digestible protein and 4.4 therms of net energy are required, while for 

 a 1,000-lb. horse only 1.0 lb. of digestible protein and 7.0 therms of net 

 energy are needed. Tho the second horse weighs twice as much, it does 

 not take twice as much feed to maintain him. 



Bull and Emmett of the Illinois Station ^ have recently made a com- 

 prehensive study of the American investigations in fattening lambs, 

 and have presented feeding standards based thereon. These standards, 

 which are given with the Armsby standards in Appendix Table VIII, 

 are similarly expressed in therms of net energy, but give the amount of 

 digestible crude protein required, instead of the amount of digestible 

 true protein. 



Ration for maintaining the steer. — To illustrate the method of using 

 the Armsby standards and table of net energy values, let us compute 

 a ration for maintaining a mature steer weighing 1,000 lbs., when 

 neither gaining nor losing weight, assuming that there are available 



2 111. Bui. 166. 



