It will be noted that the incidence of "breaks" increased during the war years 

 and has been on the decline since the end of the war. Just what factors played a 

 role in this increase is a matter of conjecture. It is hoped that the number of 

 "breaks" can be kept to a minimum. 



Flock owners and commercial hatcherymen should observe the following 

 measures in order to establish and maintain a pullorum-free flock. 



1. All the birds on the premises should be tested each year. 



2. If infection is present, the entire flock should be retested within four to 

 six weeks until a negative report is obtained, prov-ided the value of the birds 

 justifies the expenditure. 



Table 3. Appearance of Infection in Flocks Previously Negative 



♦Represents retests 



