MILK SECRETION 13 



The amount of milk and fat secreted an hour at different 

 times in the twenty-four hours is not the same. The following 

 table shows that the amount of milk secreted during the night 

 in Period II was 1.041 lb. an hour and of fat .039 lb., while 

 the amount secreted an hour up to noon was 1.23 lb. of milk 

 and 0.74 lb. of fat. 



It may be stated that the shorter the time between milk- 

 ings, the larger the amount of milk and fat secreted an hour. 

 This extra amount secured may be due in part to the additional 

 manipulation of the udder by the hand of the milker as a result 

 of additional milking, but the nervous condition of the cow is, 

 no doubt, a factor. 



In the table is given the amount of milk and fat secreted 

 by each cow an hour when the cows were milked twice and 

 three times a day. When milked twice a day, the amount of 

 milk secreted an hour was .977 lb., and when milked three 

 times, 1.10 lb. When milked twice, the amount of fat secreted 

 was .0446 lb. an hour, and when milked three times, .056 lb. 

 It will be noticed, however, that in the morning, after an inter- 

 val of twelve and one-half hours, the amount of milk secreted an 

 hour was 1.041 ; at 11 a.m., after an interval of five and three- 

 fourths hours, the amount secreted was 1.23 lb.; and at 4.45 

 p.m., after an interval of five and three-fourths hours, the 

 amount secreted was 1.12 lb. Similar variations appear in 

 the secretion of fat. At the noon hour the percentage increase 

 in the hourly secretion of milk and of fat, as compared with 

 the hourly secretion when milked twice a day, was 26 per cent 

 more milk and 66 per cent more fat. The percentage increase 

 in the hourly secretion of fat up to the noon hour as compared 

 with the morning hour was 89 per cent more fat, while the 

 secretion of milk was only 18 per cent more. This difference is 

 attributed by the writer to the nervous condition of the cow 

 due to the unusual hour of milking. The average Babcock 

 test of the cows at noon during the five days of Period II 



