412 COMPUTING THE RATION FOR FARM ANIMALS 



cent milk daily, the required ration would be (P = protein; C. H. 



= carbohydrates) : — 



P. C.H. Fat P. C.H. Fat 



(.0467 .214 .0159) X 40=1.868 8.56 .636 



(.07 .7 .01 )x8.50 = .595 5.r5 .085 



Ration required, 2.463 14.51 .721 



A ration like this should be largely composed of grain so that it 

 will not contain so much bulk that the cow will go off her feed, and 

 yet furnish the nutrients required. Cows do not require a uniform 

 nutritive ratio, but the ratio varies according to the quantity of milk 

 and weight of cow. To illustrate, let us suppose a cow weighing 1200 

 pounds and yielding 20 pounds of milk daily, and one weighing 850 

 pounds yielding 40 pounds of milk, both testing 4 per cent fat : 



P. C. H. Fat 



Nutrients for 1 lb. of 4 per cent milk, .0467 .214 .0159 

 Nutrients for 1 cwt., maintenance, .07 .7 .01 



For cow weighing 1200 lbs. and yielding 20 lbs. of 4 per cent milk : 



P. C. H. Fat 



Nutrients for 20 lbs. milk, .93 4.28 .32 



Nutrients for 12 cwt. maintenance, .84 8.40 .12 



Ration required, 1.77 12.68 .44 



Nutritive ratio, 1 : 7.7 



For COW weighing 850 lbs. and yielding 40 lbs. of 4 per cent 



milk : 



P. C. H. Fat 



Nutrients for 40 lbs. of milk, 1.87 8.56 .64 



Nutrients for 8.5 cwt. maintenance, .59 5.95 .08 



Ration required, 2.46 14.51 .72 

 Nutritive ratio, 1 : 6.5 



But if the cow weighing 12 cwt. yields 40 lb. of milk per day and 

 the cow weighing 8.5 cwt. yields 20 pounds, the nutrient require- 

 ments for their respective rations according to table will be as 

 follows : 



