66 



PRACTICAL DAIRY BACTERIOLOGY 



amount of dust will arise and spread through the air of the 

 stable. Such dust is crowded with bacteria, many of which 

 are alive and ready to grow. The common practice of keeping 

 the cattle in the same room where they are milked is thus very 

 productive of a large source of air bacterial contamination. 1 

 The number of bacteria coming thus from the air varies im- 



FIG. 34 POORLY-KEPT COW BARN, SURE TO GIVE HIGH BACTERIAL 

 CONTACT TO MILK 



mensely with the conditions of the stable. It is largest during 

 and immediately after the feeding, especially when cows are 

 fed upon dry food. The longer the time elapses after 

 feeding, and the longer time the bacteria have to settle 

 to the floor, the clearer the air becomes. But in the 

 crowded conditions of the stables and the constant motion 

 of the animals and their attendants, the bacteria never 

 settle entirely out of the air and will always be a source 



1 Barthel. Rev. Gen. d'Lait, V., p. 505, 1902. 



