ISTew York Agricultural Experiment Station. 79 



(S) who was actually present at a very considerable proportion 

 of the milking periods. 



EFFECT OF MACHINE MILKING ON FLOW. 



In 1907 the Station herd was milked by machine. A compari- 

 son of the milk flow during that season with the corresponding 

 yields for the preceding period of lactation is open to criticism 

 since the weather conditions each season markedly influenced the 

 quality of the available food supply. Accordingly as the cows 

 began their lactation period in 1908 they were divided into two 

 groups, one of which was milked by machines and the other by 

 hand. In forming these groups care was exercised to divide the 

 herd as evenly as possible with regard both to the age of the cows 

 and their general productivity. 



At each succeeding period of lactation the manner of milking 

 was changed so that each cow was milked by machine and by 

 hand during alternate periods, and during any given season ap- 

 proximately the same number of cows were being milked by each 

 method. 



The progress of this test was necessarily disturbed by the mis- 

 haps incident to handling a dairy herd. The disturbances in milk 

 flow due to abortion make it desirable to omit a period of lactation 

 from th,e comparisons in the case of six cows. Sterility, accidents 

 and the weeding-out process which is constantly going on in all 

 good herds also led to the sale of a number of animals. These 

 changes not only resulted in a reduction in the amount of com- 

 parable data but they tended also to destroy the balance between 

 the two groups of animals during any given year. In order to 

 correct these evils as fully as possible the removals from each 

 class were replaced by heifers as fast as they became available. 



The records obtained by comparing 29 cows during two or more 

 periods of lactation are given in Table II. In the column of 

 yields in this table, H and M indicate respectively, hand and 

 machine milking. 



