TTew York Agricultural Experiment Station. 87 



During their lactation periods beginning in 1906 the cows 

 were milked bj hand and during 1907 by machine. A compari- 

 son of the results for these two years is open to the criticism that 

 they may have been influenced by seasonal variation. Beginning 

 with their periods in 1908 one-half of the cows were milked by 

 each method to meet this objection. However, comparison in 

 yields could not be made in 1908 for the cows milked by machine, 

 since these cows had also been milked by machine in 1907 ; so 

 these yields do not appear in this table until the following year. 

 Beginning with the comparison for 1908-1909 the data is so ar- 

 ranged as fairly to neutralize the influence of seasonal variation 

 upon the yield. 



Considering the results shown under the head of group balances 

 and noting the variations of yield of the members of the given 

 group it will be seen that in four of the six groups there is at 

 least one cow whose variation in yield in successive years is 

 greater than the group balance. Under such circumstances the 

 elimination of this variable cow from any of the above groups 

 would have caused the group balance to favor the opposite method 

 of milking. 



It will be seen from the record of Cows Nos. 1 and 13 as given 

 in Table II that these large variations in yield are not necessarily 

 connected with the manner of milking. During the successive 

 seasons when these cows were milked by machine tliey varied 

 1,000 and 1,500 lbs. respectively. 



Moreover these seasonal variations in the yields are in perfect 

 accord with ordinary experience among hand-milked cows. The 

 data on earlier yields during succeeding lactation periods in the 

 Station herd were burned with our bam in 1904 and similar data 

 on the basis of lactation periods have not been found in Station 

 literature. However data for the yields during two successive 

 calendar years are available for 13 cows in the Annual Reports 

 of the Maine Station^ for 1897 and 1898. The total yield of 



iGowell, G. M. Herd records. Me. Agr. Exp. Station An. Reps. 13 (1897) : 

 192-200. 1898; and 14 (1898): 148-157. 1899. 



