12 



CITY MILK SUPPLY 



are milked four times daily. Whether frequent milking pays depends 

 on the value of the record and commercially, on the value of the product. 

 In Denmark, where labor is cheap cows are milked thrice daily but in 

 the United States, it is the custom to milk but twice. When the interval 

 that intervenes between milkings is the same, there is little difference in 

 the morning and evening milk, but usually the period between the even- 

 ing and morning milking is greater than that between the morning and 

 evening, with the result that the morning milk is generally somewhat 

 greater in amount and runs a little lower percentage of butterfat than 

 the evening milk. Richmond compiled the average for 17 years of morn- 

 ing and evening milk where the mean intervals of milking were 10.8 

 and 13.2 hr. with the result given in Table 6. 



TABLE 6. PERCENTAGE COMPOSITION OF MORNING AND EVENING MILK 1897- 



1913 (RICHMOND) 



In milking, the percentage of butterfat increases steadily from the 

 first milk drawn to the strippings, so that there is considerable difference 

 between the character of first and the last milk drawn. This is illustrated 

 by the figures given in Table 7. Hence it is important to milk out the 

 cows thoroughly to get the rich milk. Moreover, if this is not done, the 

 level of production of the herd tends to drop. 



TABLE 7. AVERAGE PERCENTAGE OF CONSTITUENTS OF FOREMILK AND STRIPPINGS 



(ECKLES AND $HAW) 



Variation in Milk from Milking to "Milking. Eckles and Shaw found 

 that the milk of a single cow from milking to milking is subject to the 

 following variations. The protein varied little, for no sample varied 

 0.3 per cent, from the average of the animal supplying the samples and 

 over 90 per cent, of the samples showed a variation of less than 0.2 per 

 cent, from the average. Only exceptionally would such variations be 

 of moment from the food standpoint. The sugar is commonly held to 

 be the least variable constituent of milk but it was found to vary more 

 than the protein. The milk of some animals showed a much wider 



