The Dairy Cow Scientific Findings. 



381 



later, and that as a rule the further advanced a cow is in lactation 

 the more food she requires for a given quantity of milk. When 

 first fresh the cow usually draws on her own body substance for nu- 

 trients used in milk production, and later she is nurturing an un- 

 born calf. 



Effect of advancing lactation on economy of production. 



The combined studies of Carlyle and Woll at the Wisconsin Sta- 

 tion, 1 Beach at the Connecticut (Storrs) Station, 2 and Linfield of 

 the Utah Station 3 on the normal monthly decrease in the milk flow 

 are averaged in the following table: 



Period Per cent 



First month ... 



Second month 5.8 



Third month 8.4 



Fourth month 7.3 



Fifth month.. 6.7 



Period Per cent 



Sixth month 6.1 



Seventh month 8.5 



Eighth month 10.9 



Ninth month 12.3 



Tenth month.. 11.9 



It is shown that the monthly decrease in milk flow ranges from 

 about 6 to 9 per ct. up to the eighth month. The decrease then rapidly 

 becomes larger until it amounts to about 12 per ct. in the ninth and 

 tenth months, after which the cows are generally dried off. This table 

 enables one to calculate the probable yield of a cow during any 

 month she is giving milk. 



600. Period of greatest yield. Haecker of the Nebraska Station 4 

 studied 239 lactation periods with cows at the Nebraska and Minne- 

 sota Stations, the records beginning 4 days after calving. He found 

 that 90 per ct. of the cows made their best records during the first 

 10 weeks of lactation, and over one-half during the first month. The 



1 Bui. 102. 



Bui. 29. 



Bui. 68. 



* Bui. 76. 



