In the group tested for three or more consecutive years, there were 212 flocks, 

 representing 959,757 tests, of which 0.006 percent were positive. All flocks were 

 classified as negative at the end of the testing year. Two flocks were infected, but 

 the infection was eliminated through retesting before the termination of the season. 

 The average number of birds to a flock in this group was 4,406. 



For all four groups 272 flocks were tested, representing 1,093,056 birds and ) 

 1,144,832 samples, of which 0.01 percent were positive. The 254 flocks that were 

 100-percent tested and nonreacting contained 1,040,327 birds or 95.18 percent of ! 

 the total birds tested. One flock was classified as positive. The percentage of reac- 

 tors among these birds was 3.24. 



During the past year 52 or 18.25 percent of the flocks tested in 1955-56 were not 

 tested. Annual testing of flocks is necessary to determine the pullorum status of 

 flocks. If flock owners find it necessary to omit testing for a year or more, they 

 should procure replacement stock from officially recognized pullorum-passed and 

 pullorum-clean flocks. Adequate precautions should be taken against the introduc- 

 tion of infection. 



APPEARANCE OF INFECTION IN FLOCKS PREVIOUSLY NEGATIVE 



Pullorum infection was detected in one flock that had been negative for six 

 consecutive years. The percentage of reactors detected was 2.49. The source of 

 the infection was not established, although the reactors were confined to certain 

 age groups and breed in the flock. Four tests were required to eliminate the infec- 

 tion from the flock. 



Table 3 lists the incidence of "breaks" among Massachusetts tested flocks 

 during the past 16 years. 



Flock owners and hatcherymen should constantly observe the strictest vigilance 

 against the introduction and spread of the disease. 



The following measures have been eff"ective in establishing and maintaining 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, provided the value of the birds justifies 

 the expenditure. 



3. Every reactor, regardless of its value, should be removed from the premises 

 and sold for slaughter immediately upon receipt of the report. 



4. Offal from all birds dressed for market or for home consumption as well as 

 dead birds that are not fit for consumption should be burned. 



5. The poultry houses, runs, and equipment should be thoroughly cleaned 

 and disinfected immediately after removal of reactors. An empty pen to each 

 house should be provided to facilitate cleaning and disinfection during the winter 

 months. Disinfectants approved by the United States Department of Agriculture 

 should be used. 



6. Birds removed from the premises to egg-laying contests, exhibitions, etc. 

 should be held in quarantine and determined free of disease before they are read 

 mitted into the flock. 



