No. 7. DEPARTMENT OF AGRICULTURE. 121 



THE VACCINATION OF CATTLE AGAINST TUBERCULOSIS. 



''It is not mv purpose to attempt a discussion of the general sub- 

 ject of tuberculosis of cattle or the relation of this disease to the 

 public health, for you have invited me to give an account of the 

 work that has been done under the auspices of the Pennsylvania 

 State Livestock Sanitary Board upon the immunization of cattle from 

 tuberculosis, and it will require as much time as is available to 

 properly present this part of the great tuberculosis question. Still, 

 it may not be inappropriate in passing to refer briefly to some of 

 the more recent developments in the broader field in so far as this 

 will throw light on the trend of scientific development in relation 

 to this subject and help to make clear the principles underlying and 

 the reasons f*>r the application of vaccination against tuberculosis 

 of cattle. 



''The economic importance of tuberculosis of cattle is becoming 

 greater each year. This is partly due to the greater prevalence of 

 this disease, in most states and, therefore, to greater actual destruc- 

 tion from it, and is partly due to more complete recogniton by breed- 

 ers to the necessity for controlling it. 



"There can be no profit or satisfaction in breeding or propagating 

 tuberculosis. Yet this is what many breeders are doing. And it 

 is what many have done until the disease developed so much faster 

 than the cattle upon which it might feed that herds have been 

 wiped out or so depleted that they could not be maintained profit- 

 ably. In other cases, the disease is controlled to such an extent that 

 it does not destroy the herd-outright but it may be constantly eat- 

 ing into its substance, every now or then a cow or promising heifer 

 will be observed to lose condition from no cause that is apparent until 

 it becomes necessary to dispose of her, or she may die ; few cows in 

 an infected herd reach advanced age, there is a general lack of stam- 

 ina and of productivity with occasional complete losses. It is dis- 

 couraging to have to depend on such a herd, the outcome of each in- 

 dividual is so uncertain, it is like always pulling up stream. 



"Some breeders have been so fortunate as, without effort or plan, 

 to have escaped the infection of their herds, but such men are few 

 and, where there is much interchange of cattle with other breeders, 

 infection is avoided only by the most careful watchfulness and by 

 the use of certain special measures, the principle of which is based 

 on the intelligent use of the tuberculin test. 



''It is gratifying to know that tuberculosis is not hereditary and 

 that calves from infected cows may be reared in health by protecting 

 them from contact with the germs of this disease. This has been 

 abundantly proven. It has however been so extremely difficult to 

 bring this fact home, and to lead to its being acted on that it has 

 not served the purpose that it ought to serve. The Bang system for 

 controlling tuberculosis is based on this principle. But it is important 

 to note that the Bang system has never been widely used outside 

 of Denmark and its use is diminishing rather than growing in that 

 country. This is not because it is not effective — it is effective — but 

 because it involves extra labor, watchfulness, care and expense for 

 such a long time that only a few herd owners have the courage and 

 perseverance to carry it out. It is unfortunate that this is so for 

 this system furnishes a method to gradually eradicate tuberculosis 



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