Table 2. Annual Testing Versus Single and Intermittent Testing 



It is hoped that in the future flocks will be tested annu.ally, for intermittent 

 testing is not a sound procedure for the establishment or maintenance of pul- 

 lorum-free flocks. 



APPEARANCE OF INFECTION IN FLOCKS PREVIOUSLY NEGATIVE 



Reactors were found in seventeen flocks which had been non-reactin?; the 

 previous season. Table 3 gives the testing results for these flocks. Five flocks 

 had been negative for one year, five for two years, two for three years, and the 

 remaining five for four, six, eight, eleven, and fourteen years, respectively. 



Nine flocks had less than 0.5 percent reactors on the first test. Two flocks 

 had more than 3 percent reactors. Twelve flocks obtained a negative test through 

 partial or 100 percent retests. The majority were negative after one retest. 

 One fl.ock failed to obtain a negative test through rete^ting. Four flock= were 

 not retested In nine flocks the source of the infection was unknown. In the 

 other eight flocks the infection was attributed either to the purchase of 

 questionable stock or to failure in observing adequate preventive measures. 



The matter of "breaks" has been of concern to flock owners and those persons 

 associated with testing programs. The following summary gives the incidence 

 of "breaks" among Massachusetts-tested flocks for the past eight years. 



