136 THE BUSINESS OF DAIRYING 



mately i 7.5. But since animals vary in productive 

 powers, and since this variation is not in proportion 

 to weight of body, it follows that if rations are ad- 

 justed to the actual requirements of animals the 

 nutritive ratio of the rations will also vary. 



The tables of nutrients required to a pound of 

 milk ranging in per cent, fat from 2.5 to 6.5, are 

 printed on pasteboard cards 7^Z^^2 inches, and on 

 the reverse side a table giving the nutrients in a 

 pound of ordinary feeding stuffs. Given the daily 

 yield of milk in pounds, its per cent, of butter fat, 

 and the weight of the cow expressed decimally, it is 

 an easy matter to determine the required ration. As 

 an illustration, suppose a mature cow weighs 825 

 pounds, gives 20 pounds of milk daily, testing 4 per 

 cent, butter fat. One pound of 4 per cent, milk re- 

 quires of protein .0467, carbohydrates .214, and of 

 ether extract, .0159. Multiplying these factors by 20 

 it is found that for the production of milk she needs 

 .934 of protein, 4.28 of carbohydrates and .318 of 

 ether extract. For food of maintenance multiply 

 .07 protein, .7 carbohydrates and .01 of ether ex- 

 tract (maintenance formula) by 8.25, which gives 

 protein .578, carbohydrates 5.78 and ether extract 

 .082 ; adding to this the nutrients required for milk 

 production, we have 1.51 of protein, 10.06 carbohy- 

 drates and .40 ether extract, the nutrients required 

 in the ration. They should be supplied in such 

 manner with reference to bulk that it will satisfy 

 the appetite. A ration like this should be largely 

 made up of roughage. 



But suppose a cow weighing 850 pounds yields 



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