134 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE. 



in which he resides and then be approved by the chief of the Bureau 

 of Animal Industry. Followin<^ this phin 6,G33 practitioners have 

 been listed as authorized for interstate work. Under their super- 

 vision 210,250 cattle were tested during the year, and 3,360 reactors, 

 or l.G per cent, were removed. 



During the year 54,724 cattle were tested at public stockyards 

 under regularl}' employed inspectors, and 1,417 reactors were re- 

 moved. In accordance with the regulation requiring that a permit 

 be issued for the interstate movement of known tuberculous cattle 

 for immediate slaughter or for return movement to the original 

 owner for breeding purposes, permits were issued covering 5,466 

 reactors for immediate slaughter and 107 for return to original 

 owners. 



METHODS OF TESTING. 



In previous years the subcutaneous tuberculin test has been prin- 

 cipally employed in testing animals»for tuberculosis. Scientific in- 

 vestigation in recent years has developed the intradermic and oph- 

 thalmic methods of applying the tuberculin test. As practical ex- 

 periments in the bureau's work demonstrated the value of these lat- 

 ter methods, the intradermic test was recognized March 1, 1920, as 

 official under the accredited-herd plan, to be employed as the first 

 test of herds in States where the State officials gave their approval. 

 It has also been recognized for testing cattle for interstate movement 

 to States whose officials accept certificates of that character. It is 

 believed that this method, used in combination with the ophthalmic 

 test or the subcutaneous test, will greatly expedite the work in a 

 number of States where the inspectors have been unable to keep pace 

 with the applications for testing. 



TESTING IN THE DISTRICT OF COLUMBIA. 



The District of Columbia is kept practically free from bovine tu- 

 berculosis as a result of work carried on in cooperation with the Dis- 

 trict health department continuously since 1909. During the past 

 fiscal year 292 lots of cattle comprising 1,173 head were tested, and 3 

 reactors, or approximately one-fourth of 1 per cent, were removed. 

 This low percentage affords a striking contrast with the 18.87 per 

 cent of diseased cattle found in 1910. The 3 infected animals had 

 been brought into the District on health certificates and later reacted 

 to a retest. Of the 1,173 animals tested, 516 received the subcutaneous 

 test' alone, 294 the intradermic test alone, while 363 were tested by 

 both the intradermic and subcutaneous methods. In addition 222 

 lots of cattle containing 425 head were tegted for entry into the Dis- 

 trict of Columbia and 18 reactors were removed, 



CONFERENCES ON TUBERCULOSIS. 



A general conference on tuberculosis, arranged by State and 

 Federal livestock sanitary officials, was held at Chicago on Octo- 

 ber 6, 7, and 8, 1919. A large number of interested persons attended, 

 and the results were very beneficial to the progress of the campaign. 

 The proceedings of the meeting were published in pamphlet form and 

 widely distributed. It is planned to hold such conferences, some 

 regional and some national, from time to time. 



