First Tests and Retests of 69 Flocks. — Sixty-nine flocks were retested dur- 

 ing the season. Some flock owners retested by the pen method, whereas others 

 retested all the birds in the flock. The latter plan is to be recommended for 

 eradication because the true status of the floct can be determined only if all 

 the birds on the premises are retested. 



The range in percentage of infection among the 69 flocks at the time of 

 the first test and subsequent retests is summarized in Table 4. In the dis- 

 cussion these flocks are considered in groups classed according to the per- 

 centage of infection. 



In the no infection group six flocks were non-reacting on the first and 

 second tests. Among the six flocks, two were experimental pullet flocks which 

 had infection last season but were non-reacting before the end of that season. 

 This indicates that the infection was successfully eliminated from the prem- 

 ises. The remaining four flocks were subjected to additional tests to deter- 

 mine the exact status of the birds. 



Thirteen flocks, representing 20,048 birds, revealed less than 1 per cent in- 

 fection. On second test ten flocks, representing 3,117 birds were non-reacting. 

 The remaining three were positive. Two of these were tested the third time 

 and found non-reacting. 



In the 1 to 5 per cent infection group there were 29 flocks, representing 

 28,472 birds. Seven flocks were non-reacting on second test. Of the 22 posi- 

 tive flocks 3 were non-reacting on the third test, 4 were positive, and 15 did 

 not test. 



Eight flocks, representing 12,277 birds, revealed from 6 to 10 per cent in- 

 fection. One flock was non-reacting on second test and seven were positive; 

 only two tested the third time, both revealing reactors. 



One flock had 11 to 15 per cent infection and upon retest remained posjtive. 



In the 16 to 20 per cent infection group there were three flocks; one was 

 non-reacting on second test, the other two positive. One revealed no reactors 

 on third test and the other did not test. 



Five flocks in the 21 to 25 per cent infection group were positive on second 

 test. Only two tested more than twice, one being non-reacting on third test 

 and the other on fifth test. 



In the four groups having more than 25 per cent infection, four flocks were 

 positive on the second test, of which three were non-reacting on third test, 

 while one did not test the third time. 



One non-reacting flock classified under the fourth test was negative on the 

 third test, and one flock classified under the fifth test was negative on fourth 

 test. 



Of the 69 flocks retested, 36 became non-reacting. Of this number 25 were 

 successful in obtaining a non-reacting report on the second test, while 11 re- 

 quired three or more tests. 



♦ Consecutive Annual Testing Versus Single and Intermittent Testing 



More poultrymen are beginning to realize that annual testing is necessary 

 in the eradication of pullorum disease. Moreover, there is no assurance that 

 a flock once free of infection will remain so, except by annual testing and 

 careful preventive measures. This may be determined from the data in Table 



