CHAPTER IV 



BOVINE TUBERCULOSIS AND OTHER CATTLE 

 DISEASES. 



Bovine tuberculosis. The subject of bovine tuberculosis and 

 its relations to the milk supply cannot be adequately discussed 

 without a consideration of the relations of the disease in its 

 purely economic aspects. 



Losses to the live stock industry. The disease is a tremendous 

 source of loss to the live stock industry, and worse \-et, the 

 majority of those men suffering the loss have not awakened to 

 the idea of the possibility of [irevention. Precautions for the 

 control of tuberculosis have not yet been .generally recognized 

 as a necessary detail in the management of the live stock or dair>- 

 business. Losses are sustained by the decrease in production 

 from diseased animals by death, loug before the exi)iration of 

 the natural life period, and by condemnation of carcasses in 

 the abattoir, in cases where an adequate meat inspection s>-stem 

 is maintained (17). These facts have been recognized by a 

 few, and the means of transmission have been determined, even 

 though the facts have not been acted upon in the United States 

 extensively enough to check the disease. 



Trausiuissioii by milk. Milk is one great factor in the spread 

 of tuberculosis among cattle. Slaughter-house statistics gath- 

 ered from observations on pregnant animals have demonstrated, 

 if such demonstrations were needed, that tuberculosis is very 

 rarely inherited. The common practice in raising dairy cah-es 

 has been for a long time to separate them from the cows early 

 and feed them on skim-milk. It is under these conditions that 

 an ai)palling amount of infection of calves occurs (37). The 

 recognition of this source of tuberculosis and its elimination 

 by heating the milk, has afforded the basis for the most prac- 



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