350 ELEMENTS OF AGRICULTURE 



241. Butter-making on the Farm. 



350. The Dehorning of Cattle. 



258. Texas, or Tick Fever, and Its Prevention. 

 206. Milk Fever. 



351. The Tuberculin Test of Cattle for Tuberculosis. 



Types and Breeds of Farm Animals, by C. S. Plumb. Pp. 175-332. 

 Cyclopedia of American Agriculture, Vol. Ill, pp. 4-44, 122-162, 

 176-272, 301-382. 



SUPPLEMENTARY NOTE TO PAGE 339 



It has been shown that only a few of the cows that have tuberculosis 

 have their udders infected. From this the erroneous conclusion has 

 often been drawn that milk from such cows is not likely to be infected. 



Tuberculous cows expel tubercle bacilli mainly with the excreta 

 from their bowels, but also with material slobbered or discharged from 

 their mouths and noses, and in some cases bacteria are contained in 

 the milk. 



The most serious source of danger to milk is from the manure that 

 gets into it. A hair that falls into the milk may look clean, but it may 

 carry small particles of manure, and if the cow has tuberculosis this 

 manure is quite likely to contain the germs of the disease. As well as 

 being a strong argument for healthy cows, this is an additional reason 

 for keeping milk clean it is not merely a matter of sentiment. 



Work done at the Experiment Station of the Bureau of Animal 

 Industry has shown that cows, seemingly in good health but which had 

 reacted to the tuberculin test, were expelling myriads of tubercle 

 bacilli from their bowels. Analysis of milk supplied to a certain city dis- 

 closed that fully one sample in twenty was infected with tubercle bacilli. 

 Experimental work carried on with butter showed that the germs will 

 remain alive and virulent in the ordinary salted butter for nearly six 

 months. 



Hogs that eat manure from tuberculous cattle are almost certain to 

 become infected. 1 



'United States Department of Agriculture, Yearbook, 1908, pp. 217-226. 



