46 ILLINOIS STATE DAIRYMEN'S ASSOCIATION 



I want to say this much: Tuberculin, the substance 

 used to test cattle with, is a sterile product. It contains no 

 bacteria and absolutely can not harm healthy cattle. With- 

 out tuberculin the reduction of tuberculosis would be a 

 hopeless task. 



I also want to say this: The tuberculin test is not 

 100% perfect, it is not absolute proof, but it is the best 

 science has been able to give us. It is the most accurate of 

 all biological products known to science in the way of test- 

 ing disease. 



The man who depends upon tuberculin alone to reduce 

 tuberculosis in cattle is lost, because he will find some ani- 

 mals that will not respond to this test. 



Any animal that has tuberculosis will have a certain 

 amount of this natural tuberculin formed in its system from 

 it and, under ordinary- conditions, the system will throw it 

 off. If an animal is extensively infected and the amount 

 produced is large, when we inject a very small amount, 

 about three drops, to determine whether the animal has 

 tuberculosis, we have so much natural tuberculin there that 

 the amount is offset. Especially do we find that in the dairy 

 sections where infections are extensive and our inspections 

 take cattle on general principles, that is, on physical exam- 

 ination. 



With the co-operation of herd owners, we are some- 

 times given information on which we can act intelligently 

 in making these tests. 



I want to cite an incident. There was a herd up in the 

 dairy district of Northern Illinois, consisting of 110 cattle, 

 nearly all pure-bred. 



The first time we tested we took eight or nine. Within 

 sixty days we took nine more. Among those that were left, 

 we got several reactors and every time we tested there were 

 four or five reactors. It was apparent that there was some- 

 thing wrong here. 



We asked the owner whether there was any particular 

 cow that he would suspect of being infected. We pointed 

 out one as a possibility, but he declared this one to be his 

 grand champion cow, the best one he had. She had already 



