DAIRY INSPECTION 131 



duced. Cows in milk should not be kept in the same 

 stable with horses or other animals; they should have a 

 separate stable for their exclusive use. There should be 

 a special stable for parturition and for cows which are 

 not in health. 



(a) Odor of the Air. On entering the stable the 

 odor of the air should be noted, since any slight abnor- 

 mality will be more perceptible at this time than later, 

 when the inspector has become accustomed to the atmos- 

 phere. The odor of the air is a good test of the efficiency 

 of the ventilation and also of the degree of cleanliness 

 of the stable, especially in cold weather when the doors 

 and windows are closed and the cows are kept in the 

 stable almost continuously. Abnormal odors in stable 

 air usually originate from two sources : exhalations from 

 the cows and decomposing manure and urine. Condensa- 

 tion of moisture on the walls, ceiling, or windows or the 

 presence of frost is another indication of defective venti- 

 lation. A moist atmosphere assists in the spread of tuber- 

 culosis in a stable. The droplets of infected saliva ex- 

 pelled by tuberculous cattle in the act of coughing float 

 more readily in the stable air when it is saturated with 

 moisture than when it is drier. In most instances cattle 

 are infected with tuberculosis by the inhalation of in- 

 fected air or by the ingestion of infected food or water. 

 Insufficient ventilation has the effect of concentrating any 

 infection in the air of a stable, while ventilation dilutes it. 



Recent experiments have shown that the harmf ulness 

 of insufficient ventilation is not due to a deficiency of 

 oxygen, an excess of carbon dioxide, or the presence of 

 organic poisons in expired air, but to the warmth and 

 moisture of the air in unventilated places and to its lack 

 of movement. A warm, moist atmosphere has a depress- 



