THE FEED REQUIREMENTS OF FARM ANIMALS 145 



Thus the requirements of a cow weighing 1100 pounds 

 and producing 35 pounds of 3.2 per cent milk are as follows : 



The ration is then calculated in the usual manner, keeping 

 in mind that the total nutriment is obtained by multiplying 

 the fat by 2.25, and adding to it the protein and carbohy- 

 drates. 



The Well and Humphrey Standard for Dairy Cows. — 

 Woll and Humphrey, of the Wisconsin Experiment Station,^ 

 have presented a standard for dairy cows based upon the live 

 weight of the cow and the amount of butter fat produced 

 daily. Their standard is given in Table 18. 



Thus to determine the requirements of a 900-pound cow 

 giving 20 pounds of 5 per cent milk daily, one first determines 

 the amount of butter fat produced daily, which in this case 

 is 1.0 pound. From Table 18, it is seen that a 900-pound 

 cow producing 1.0 pound of butter should have 22.4 pounds 

 of dry substance, 2.04 pounds of digestible protein, and 15.0 

 pounds of total digestible substance (digestible protein + 

 digestible carbohydrates + digestible fat). The ration is 

 then calculated in the usual manner. 



1 Research Bui. 13. 



