142 



PRINCIPLES OF FEEDING FARM ANIMALS 



For example, to calculate a ration according to the Haecker 

 standard for a 900-pound cow, giving 20 pounds of milk 

 daily containing 5 per cent of butter fat, the process is as 

 follows: (1) determine the maintenance requirement for a 

 900-pound cow ; (2) add to the maintenance requirement the 

 requirement to produce 20 pounds of 5 per cent milk; and 

 (3) calculate a ration to conform with this standard. Thus 

 a cow weighing 900 pounds requires 0.63 lb. of digestible 

 protein, 6.30 lb. of digestible carbohydrates, and 0.09 lb. 

 of digestible fat for maintenance. According to Haecker, 

 to produce one pound of 5 per cent milk requires the con- 

 sumption of 0.060 lb. of digestible crude protein, 0.28 lb. 

 of digestible carbohydrates, and 0.024 lb. of digestible fat, 

 in addition to the maintenance requirement. Thus the 

 total requirement to produce 20 pounds of 5 per cent milk 

 is calculated as follows : 



The ration is then calculated in the same manner as de- 

 scribed under the discussion of the Wolff-Lehmann standards. 

 The Savage Standard for Dairy Cows. — Savage, at the 

 Cornell University Experiment Station,^ after extensive 

 experiments, suggests the following standard for the mainte- 



» Bui. 32::, 



