332 PRINCIPLES OF FEFA)ING FARM ANIMALS 



Therefore, 



$1.00 worth tankage contains . 

 $1.00 worth middlings contains 



dujestiblk 

 Photein 



Lb. 



20.0 

 11.3 



Total 

 Nutriment 



Lb. 



31.9 

 53.1 



From this calculation one could not determine which feed 

 is the more economical. 



In such instances, it will be necessary to calculate the 

 cost of the ration when one of the feeds is used and compare 

 it with the cost of the ration when the other feed is used. 

 It also will be necessary to know the prices of the other 

 feeds used in the ration. Returning to the example, we will 

 assume that ear corn is worth 50 cents per bushel, and that the 

 feeder wishes to feed 100-pound fattening shotes. Accord- 

 ing to the Wolff-Lehmann standard, a ration consisting of 

 2 pounds of shelled corn and 2 pounds of middlings will 

 fulfill the requirements of a 100-pound pig. This ration will 

 cost at the assumed prices for corn and middlings, 4.8 cents 

 per day. Also a ration consisting of 3 J pounds of corn and 

 J pound of tankage will satisfactorily fulfill the requirements. 

 The cost of this ration is 4.4 cents per day. Thus, at these 

 prices, the tankage is slightly more economical than the 

 middhngs. In this particular instance it probably would 

 pay to buy both feeds for the sake of the variety. 



In comparing a concentrate with a roughage, it is better 

 to compare them on a basis of their content of digestible 

 protein and net energy rather than on their content of diges- 

 tible protein and total nutriment. The reason for this is 

 that the net energy values do not include the energy ex- 



