356 AGRICULTURAL CHEMISTRY 



483. A trial ration vj then calculated, using the approxi- 

 mate amounts of ^ous as given in the various sections 

 relating to tK<^ r oCd requirements of animals. The 

 amounts of digestible nutrients in the foods selected are 

 then calculated ?nd the total amounts of the different 

 nutrients determined. If these correspond with the 

 figures given in the table, a reasonably well-balanced 

 ration is secured. In case the nutrients are present in 

 the right proportion but deficient in amounts, the weights 

 of foods used are increased; if excessive, they are reduced. 

 Should the ration be deficient in digestible protein, a 

 small amount of some food containing a liberal supply of 

 this nutrient may be added. Finally, when the require- 

 ment as to amounts of nutrients is satisfied, the various 

 other factors as bulk, suitable combinations, cost, and 

 labor involved in preparation are to be considered. 



Example. Calculate a ration for a dairy cow. The standard 

 ration calls for 1.8 to 2 pounds digestible protein and from 10 to 

 12.5 pounds digestible carbohydrates. It is necessary to combine 

 the coarse fodders and grains so as to secure approximately these 

 amounts of nutrients. A trial ration is calculated, composed of 10 

 pounds each of clover-hay and corn fodder, 20 pounds of mangels, 

 5 of bran and 3 of oats. The digestible nutrients in these materials, 

 as given at the close of the chapter, are as follows : 



DIGESTIBLE NUTRIENTS. 



Carbohy- 

 Protein. Fat. drates, etc. 



Wheat bran 12.9 3.4 40.1 



Mangel beets i.i o.i 5.4 



Clover hay 6.8 1.7 35.8 



Corn fodder 2.5 1.2 34.8 



Oats 9.2 4.2 47.3 



These figures are on the basis of 100 pounds. The 



