Observations on the Spread of Tuberculosis Under Outdoor 



Conditions. 



In at least one respect the problem of dairy sanitation is not as 

 great in California as in many other parts of the United States. The 

 problem of proper ventilation of stables is not a great one. The 

 climatic conditions are such that tight barns are unnecessary. Most 

 dairies do have barns, but the doors and windows are left open the 

 year round. Many have no cow stables. In such cases a shed 

 without side walls is usually available to milk under during rainy 

 weather. In one of the certified dairies, that at El Monte, supplying 

 milk to Pasadena and Los Angeles, the milking barn has no side 

 walls ; the cows are seldom under a roof more than four hours a day, 

 two hours at each milking. Naturally, under such conditions it 

 would be ridiculous to put stress on the King System or other 

 devices for ventilation. In dairy cows kept under these conditions, 

 tuberculosis is common. We believe that it will spread even under 

 strictly outdoor conditions. Even in range cattle the disease seems 

 to be increasing. 3 We have already mentioned the fact that in ex- 

 posing the bovovaccinated calves and the controls to infection the 

 association and resulting infection took place entirely in the out-of- ( 

 doors. The size of the pasture was about twenty acres, the corral* 

 was about one-half an acre in size. In the corral was a watering 

 trough, but the animals also had access to a stream and an irrigating 

 ditch in the pasture. The first five tubercular cattle that were 

 secured for infecting the experimental calves were stock kept under 

 semi-range conditions. In central California are vast swampi 

 called tule lands. Much of the year these furnish excellent green 

 feed for cattle. The five cattle were selected from a band of about 

 150 cattle that had been raised in these tules. 



The probabilities are that they had never been under a roof. In 

 riding through the swamp, six animals were selected, which were 

 emaciated or coughing. On tuberculin test five of these reacted 

 and in May, 1908, they were taken to the University Farm. In six 

 months all had died of advanced tuberculosis, as proven by autopsy 

 in each case. The last of the animals died October 9, 1908, making 

 the time they were confined with the experimental calves less than 

 six months. 



In March, 1909, nine reacting dairy cows were secured. Two of 

 these were in full lactation, but were rapidly dried up. The others 

 were dry. Some of them had been tuberculin tested in February, 

 1909, and some in March, and had been removed from a certified 

 herd because of reactions. Most of them were in poor condition, 

 but under their changed conditions all but one improved in appear- 

 ance. In April one died. The autopsy on this animal was imper-, 

 fectly performed, but the lungs were noted to be calcareous. On 

 June 3, 1909, the nine remaining cows were tested with 3 cc. of 

 University of California tuberculin, and none of them reacted. On 



3 Ward and Haring, Bulletin 199, Agricultural Experiment Station, Berkeley, 

 California, August, 1908. 



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