8 



instance related in the previous paragraph for a direct reply to such a 

 question. It is true that some poultrymen have succeeded in maintaining 

 a disease-free flock by testing only the breeders every two or three 

 years, but it takes exceptional management. Sooner or later flocks tested 

 under such a plan will become infected. 



As mentioned previously, 35 of the 71 non-reacting, partially tested 

 flocks were tested for two or more consecutive years. In 1927-28 ten of these 

 were 100 per cent tested and non-reacting; 14 were non-reacting but only 

 partially tested; two had infection and were 100 per cent tested; and nine 

 had infection but were only partially tested. 



