26 



were laying. Such a plan is not conducive to eradication, according to 

 data collected in Massachusetts during the past few years. On page 13 

 of Control Bulletin 43 (the 1927-28 report), is reported a preliminary 

 project on the i)rt)j)er age to start testing birds. 



The progeny of the flock used in that project, together with a portion 

 of the same birds, were tested three times from September 14, 1928 to 

 December 31, 1928. At no time did this group of birds yield any reactors 

 to the agglutination test. At the second test on October 27th the flock 

 had been reduced from 155 birds (44 males and 111 females) to 113 

 birds (26 males and 87 females), and about 10 per cent of the females 

 were laying. On December 31, all the females were laying. Thus the 

 disease has been successfully eliminated from this flock. 



On August 20, 1928, the first test on another flock of four to five 

 months old pullets was made. At the first test on 326 pullets, none of 

 wliich were laying, 78 reactors (23.93 per cent) were detected. The flock 

 was then tested monthly until February 27, 1929, with the exception of 

 November, when the flock was suffering from a severe outbreak of chicken 

 pox. Five reactors were detected on the second test, five on the third 

 test, and one on each of the next two tests. At the February 27, 1929 

 test no reactors were detected. 



Thus, 78 (86.66 per cent) of the total 90 reactors were removed when 

 the birds were from four to five months of age. In the flock tested last 

 year and referred to above, 82.61 per cent of the reactors were detected on 

 the original test. The total reactors detected in the two flocks were 113, 

 and 97 or 85.86 per cent of these were detected on the original tests a 

 month before the pullets M'ere laying. 



One flock which has been under observation during the past year will 

 give some comparative data. This flock of 562 birds was tested for the 

 first time in November, and at that time was in about 45 per cent pro- 

 duction. Fifty-five reactors were found at the first test, and six weeks 

 later eight more reactors were detected. A third test on February 6 

 detected four reactors, and two tests on February 23 and March 19, 

 respectively, yielded no reactors. The flock was in from 50 to 65 per 

 cent production after the first test. Out of the 67 reactors detected in 

 the five tests, 55 or 82.09 per cent were eliminated by the first test. 



Many more flocks of both groups must be tested before definite con- 

 clusions can be made, but from the preliminary results obtained to date 

 it appears that one can eradicate the disease from a flock when the 

 testing is started before laying, just as efficiently as when the testing is 

 not started until the flock is in production. 



Some investigators maintain that many of the reactors detected among 

 birds that have not matured will become non-reactors, and therefore 

 advise waiting until all birds are fidly matured, and all females laying 

 before testing. This has been found to be true in a few cases under 

 observation, but the authors believe that from the standpoint of eradication 

 a small percentage of such reactors should be sacrificed, since they are 

 nearly always questionable, and therefore dangerous birds to have in 

 the flock. Furthermore, every poultryman has observed that pullets just 

 starting to lay are likely to lay eggs on the floors, dropping boards, 

 etc. In addition, a large number of soft-shelled eggs are laid on the 

 dropping boards during the night and early morning. Leaving infected 

 birds in the flock until they start to lay, increases the chance for infection 



