l62 SCIENCE AND PRACTICE OF CHEESE-MAKING 



PERCENTAGE OF CASEIN IN MILK OF DIFFERENT BREEDS 



OF COWS 



Name of breed Per cent of casein in milk 



Holstein-Friesian 2.20 



Ayrshire 2.46 



American Holderness 2.63 



Shorthorn 2.79 



Devon 3.10 



Guernsey 2.91 



Jersey 3.03 



Influence of stage of lactation on the percentage 

 of casein in milk. — We will first present results 

 representing the average of about lOO lactation periods 

 of individual cows and then the results representing 

 work done at the New York experiment station in 

 connection with cheese-factories in New York state, 

 already referred to: 



VARIATION OF PERCENTAGE OF CASEIN IN MILK WITH 



ADVANCE OF LACTATION 



According to these results, the percentage of casein 

 decreases in the second month of lactation, as com- 

 pared with the first, and then begins to increase, con- 

 tinuing to increase month by month to the end of the 

 lactation period. The behavior very closely resembles 

 that of fat. 



