94 



FEEDS AND FEEDING, ABRIDGED 



corn stover, oat straw, dent corn, and cottonseed meal. According to 

 the standard, an animal of this weight requires 0.5 lb. digestible protein 

 and 6.0 therms of net energy. As corn stover and oat straw are much 

 cheaper than the concentrates, let us first see how nearly a ration of 

 these roughages alone will meet the requirements. Suppose that we 

 select for a trial ration 8 lbs. of oat straw and 10 lbs. of corn stover. 

 The calculations will then be as follows : 



Calculations for trial ration for maintaining 1,000-lb. steer 



Corn stover 

 In 100 lbs. In 10 lbs. 



Dry matter . . .81.0 H- 100 X 10 = 8.10 

 Dig. protein. . . 1.6 -=-100 X 10 = 0.16 

 Net energy... 31.62 -f- 100 X 10 = 3.16 



Oat straw 

 In 100 lbs. In 8 lbs. 



Dry matter 88.5 -H 100 -X 8 = 7.08 



Dig. protein 0.8 -r- 100 X 8 = 0.06 



Net energy 34.81 -i- 100 X 8 = 2.78 



First trial ration for maintaining 1,000-lb. steer 



This ration furnishes enough net energy but is deficient in digestible 

 protein. Corn, which is high in net energy but low in protein, will not 

 improve the ration, while cottonseed meal, which is rich in protein, will 

 make up the deficiency. Let us therefore substitute 1 lb. of choice 

 cottonseed meal for 2 lbs. of oat straw. We then have : 



Second trial ration for maintaining 1,000-lb. steer 



This ration agrees closely with the standard in digestible protein and 

 net energy value. Thus, according to the Armsby standard, a satis- 

 factory ration for maintaining a 1,000-lb. steer may be composed of 

 10 lbs. corn stover, 6 lbs. oat straw and 1 lb. choice cottonseed meal. 



