New York Agricultural Experiment Station. 127 



PLAN AND PURPOSE OF THIS INVESTIGATION. 



It has been the purpose of this investigation: (1) To make a 

 number of examinations of the milk of individual animals in order 

 to determine the normal number ri cells present in the milk. These 

 studies are supplementary to those made by Breed and Stidger. 38 

 (2) To make detailed examinations of the milk of individual cows 

 in the hope that some reason could be discovered for the known 

 variations. (3) To study the influence of the milking machine on 

 the number of the cells present in the milk. 



The animals whose milk was examined were largely from the 

 Station herd. This herd is of especial interest because the records 

 of the animals have been well kept so that their history is known. 

 Moreover, part of the herd was milked by machine and part by 

 hand. This gave an excellent chance to do experimental work to 

 determine the influence of machine milking on the cell content of 

 the milk. 



The Station herd consisted of 25 full blood and nearly full blood 

 Jerseys at the time these examinations were made. The herd was 

 free from tuberculosis but, in spite of careful management, was not 

 free from troubles due to abortion and sterility. The stabling of the 

 cows was excellent and the herd as a whole free from udder troubles. 

 No three-teated cows were in the herd and only three whose record 

 shows a history of udder troubles of any kind. [Chloe B. (No. 7), 

 Hammond F. 2 (No. 1G), and Millie of Geneva (No. 19).] During 

 the six weeks in which a majority of these tests were made, the author 

 of this paper was present at all but a few milkings and kept a care- 

 ful watch for gargety milk but discovered none. 



Records of the animals studied are given in Table I so far as they 

 are pertinent to this investigation. Other records of some of these 

 cows are given in Bulletin 322 of the Station. 



The animals whose names are printed in the table in bold face type 

 are registered full blood Jerseys. The " Hammonds " are also believed 

 to be full blood Jerseys, but are not registered. The others are 

 grade Jerseys. 



Gerty F. 2 (No. 12), Millie D. of the Station (No. 18) and Ruth F. 

 (No. 24) were the animals used in the experiment with the increased 

 vacuum and Gerty F. 1 (No. 10), Hammond F. 1 (No. 15), and 



88 See footnote 1. 



