326 IOWA DEPARTMENT OF AGRICULTURE 



Member: Last summer during the heated season we attempted 

 to test six or seven head of cattle, but we found the temperatures 

 were high. We tried again but still they were high and we had the 

 same trouble. We were prevented from testing until fall. Was 

 that caused by the weather? 



Dr. Roberts : Were they well fed at the time ? That would have 

 a tendency to elevate the temperature. We gave a public demon- 

 stration in Wisconsin a few years ago and we showed something 

 like three carloads. These animals were tested in August. We 

 found tuberculosis in every one of those cattle that were killed, 

 showing that the test can be applied in summer. 



]\f ember: How can you tell the difference between a good and 

 a poor tuberculin? 



Dr. Roberts: There is no way to tell. I simply said that to 

 show how people get an idea that tuberculin produces tuberculosis. 

 It does not happen very often. There is no way of knowing except 

 that you apply the test to a herd of cattle when your judgment 

 would lead you to believe that they were tuberculous. 



Member: AYould you think it advisable to test an animal when 

 she was within three or four weeks of freshening? 



Dr. Roberts: I have often tested cattle that calved during the 

 night. I have very seldom found one to react. If they should I 

 would not condemn her, but would consider her suspicious. This 

 can be applied to any animal nearing the period of freshening. 



Member: In your experience about what per cent of reacting 

 animals were found to be without tuberculosis? 



Dr. Roberts: I should say out of 100 there may be 5 per cent 

 that you might not find lesions in. All our tuberculous cattle are 

 killed under federal inspection. In one instance I applied the test 

 to a herd and found one reactor. She was in good condition. Be- 

 fore she was killed I told the inspector to look her over carefully. 

 If she had it I wanted to know where. He says I can't find a 

 thing wrong with her. Just then he split the carcass from one end 

 to the other. Right over the lungs in the spine was an abscess as 

 large as a hen's egg. It involved the spinal cord. The owner said 

 the only thing he found in this cow was that she had a stiff neck. 



Member: I presume the summer months are the best months in 

 which to make the test ? 



