25 



in tlie flocks tested for two consecutive years. Furtliermore, the flocks 

 that are following an intermittent plan of testing, — that is, testing once 

 in two or tliree years, — show more infection than the groups testing 

 consecutively. 



Results of Buying Replacements from Various Sources 



Table X is a summary of the results of buying replacements from 

 various sources. Flocks tested for the first time furnished the basis of 

 this summary. The information was obtained from the blood collectors' 

 flock reports, and from replies to a questionnaire sent to the poultrymen 

 at the end of the season. There were 145 new flocks tested, but only 

 106 of these were considered, as the information on the remaining ^9 was 

 indefinite. 



Table X. Results of Buying Replacen-.ents from Various Sources 



It will be noticed that 34. flocks, with 13,214 birds, originating from 

 known negative sources were found to be negative. Nineteen flocks, witli 

 6,584 birds, were found to be infected. Of these 19 flock owners, six 

 had known infection on the plant previous to buying new stock; two had 

 stock on the premises from unknown sources; one did custom hatching; 

 two had their eggs custom hatched; and eight gave no definite information 

 as to the conditions on the plant i^revious to the time of adding the 

 pullorum disease-free stock. From the above 11 examples it is evident 

 that adding clean stock to infected premises is not a correct procedure 

 in obtaining a clean flock. 



Seven flocks with 2,199 birds which were negative this season, came 

 from seven sources which had reactors in 1927-28. The seven sources 

 were tested in 1928-29 and five were found to be negative and two had 

 less than one per cent infection. 



Eighteen flocks with 6,103 birds which had infection in 1928-29 origin- 

 ated from sources which had reactors in 1927-28. Thirteen of the 18 

 sources were tested this season and had reactors; three of the 18 h;i,d no 

 reactors and two did not test. 



No comparison can be made in the last group of 28 flocks ns no 

 information was available as to the status of the sources of these flocks. 



The Proper Age to Start Testing Birds 



Much controversy regarding the correct age to start testing young 

 birds exists. Formerly, the young birds were not tested until the pullets 



