1920.] 



Milking Machinks 



507 



imitate the natural sucking of a calf, the writer gives 

 an 'account of the mechanism of the ordinary types. Be 

 then passes on to the question of the efficiency and suitability of 

 the machine, and records his conclusion that it may be consi- 

 dered comparable with average hand-milkers. No reduction of 

 the milk yield need be anticipated from its use. It is. however, 

 advisable to strip the cows by hand after machine milking. If 

 care is taken to apply teat-cups of the proper size, no injurious 

 effect on the health of the cows or on the teats and udder need 

 result. The saving of labour has been estimated at from 30 to 

 40 per cent., but it is not profitable to instal a milking machine 

 for less than 30 cows. 



Dealing next with the main question of his paper, the writer 

 points out that milk produced under good conditions may contain 

 less than 5,000 bacteria per cubic centimetre. The standard 

 for certified milk in the United States is 10,000 bacteria per cubic 

 centimetre. He quotes instances, however, of bacterial contents 

 of machine-drawn milk "ranging from 71,000 to 395,000 . . . 

 with as many as 1,208,000 bacteria per cubic centimetre . . . 

 a bacterial content of 509,000 per cubic centimetre when the 

 machine received only average care," and reinforces these by 

 his own experiences of 1 ' two different machines giving milk 

 with 494.000 and 1,392,000 bacteria per cubic centimetre 

 respectively." Such figures. Dr. Orr remarks, may surprise the 

 casual observer to whom a milking machine appears to be an 

 ideal method of taking milk from the cow. 



No doubt certain important sources of contamination are guarded 

 against by the use of a milking machine, but other sources arise 

 through the nature of the apparatus. Milking machines render 

 milk liable to contamination from three sources : — (1) material 

 from a diseased or gargety udder; (2) air and dirt sucked in when 

 the teat-cups fall off; and (3) the serious contamination from 

 the cups and tubes of the machine, which can be kept clean only 

 by exercising the strictest care. Contamination from the first- 

 mentioned source may be prevented by examining beforehand 

 the teats and udder of the cow t — this is an essential pro- 

 cedure in ordinary hand-milking. The second source is more 

 difficult to deal with, but if the teats are kept clean and fitted 

 with caps of suitable size, the risk of the cups falling off may be 

 reduced to a minimum. It is the third source of bacteria which 

 requires most attention. Great care should be taken to keep 

 clean those parts of the machine with which the milk comes into 

 contact, namely, the cup and its rubber parts, the " claw." the 



