BUREAU OF ANIMAL INDUSTRY. 353 



This work has demonstrated a fact of great economic value to 

 many herd owners, for together with the marked decrease in the 

 per cent of tuberculosis disclosed by annual retests there has resulted 

 a large number of entire herds which are now being maintained free 

 from tuberculosis. 



TtTBEBCULIN TESTING OF CATTLE IN THE DISTRICT OF COLUMBIA- 



The eradication of bovine tuberculosis from the District of Co- 

 lumbia, which was begun in the fall of 1909 in cooperation with the 

 Commissioners of the District, has been continued throughout the 

 fiscal year 1912 by the systematic retesting of cattle within the area 

 and the testing of cattle brought into the District from the various 

 States for dairy or breeding purposes. The actual progress which 

 has been made by the practical application and enforcement of the 

 regulations and the use of specially trained veterinarians in the 

 ■work, as herein shown, should serve as a stimulus to the tuberculosis 

 eradication work in restricted and quarantined areas, and the pos- 

 sibility of successfully conducting such work in connection wnth 

 city or town milk supplies can be recognized by a comparison of the 

 results of the first systematic testing of all cattle in the District of 

 Columbia with those of the retests now in progress. 



During the past fiscal year 773 cattle in the District of Columbia 

 were submitted to an annual retest. Of this number 763 passed, 8 

 reacted, and 2 were regarded as suspicious. These figures when com- 

 pared with the results of the first testing of cattle throughout the 

 District show that the percentage of cattle free from tuberculosis 

 has been increased from 81.13 to 98.71 per cent, while the percentage 

 of reactors and suspects has been reduced from 18.87 to 1.29 per cent. 

 Furthermore, the percentage of infected premises demonstrated by 

 the first test was 18.35, while during the past year but 3.61 per cent 

 of the premises upon which retests were applied were found to be 

 infected. 



The maintenance of such a low percentage of tuberculosis among 

 cattle in the District of Columbia is assisted by the caution with 

 which District owners purchase cattle from adjoining States, many 

 of the centers of infection having been disclosed by the results of the 

 tuberculin tests in the previous year. The sale of cattle from these 

 known infected herds has been practically stopped, as when reactors 

 are found among cattle brought into the District no reimbursement 

 is allowed, and the owners receive only the proceeds of the sale of 

 those carcasses which pass the post-mortem examination after being 

 slaughtered, as required by the order of the commissioners. 



There were entered into the District for dairy or breeding purpo.ses 

 during the year 617 cattle, of which 595 were regarded as free from 

 tuberculosis, while 21 reacted, and 1 was regarded as suspicious. 

 This .shows a percentage of reactors and suspects of 3.57, which 

 should be compared with the results of original tests in Virginia and 

 Maryland, where 18.07 per cent reacted. 



Under the provision requiring the identification and tagging of 

 cows and bulls entering the District for slaughter purposes, 827 tags 

 were attached for 33 shippers. ^ 



70481°— AGB 1912 23 



