FEEDING FOR MILK PRODUCTION 281 



The total requirements then are as follows : 



The problem is to find a ration that contains this amount 

 of digestible protein and has this energy value. Other prob- 

 lems also enter into the question, such as bulk and the com- 

 parative cost of several feeds available. In calculating a 

 ration we always begin with the roughness, since this class 

 usually furnishes the nutrients cheaper than the concentrated 

 feeds such as grain and mill products. Further, on most 

 farms considerable roughness is on hand that must be used 

 to the best advantage, and as already pointed out, the cow is 

 adapted for consuming roughness and must have a certain 

 bulk to her ration at all times. We will assume that on the 

 farm where the foregoing ration is to be fed corn silage, clover 

 hay, and corn are on hand, and wheat bran and cottonseed meal 

 may be purchased if necessary to provide the proper ration. 



A good ration of roughness in quantity would be corn 

 silage 35 pounds and clover hay 9 pounds. Using Table 10, 

 this would give the following : 



