17 



The third flock which was previously non-reacting was never 100 per 

 cent tested until 1928-29. In 1926-27, 151 birds out of the flock of 600 

 were tested and no reactors were detected. In 1927-28, 470 birds out of 

 600 were tested and 1.91 per cent infection was reported. In 1928-29 the 

 entire flock of 636 was tested and 18.08 per cent infection found. No 

 retest was made, since the owner decided to buy replacements from pull- 

 orum disease-free sources, and to sell his original stock. 



It is extremely difficult to explain breaks such as the first of the three 

 just described, but one must always keep in mind that the disease is of 

 an infectious nature, and like all such diseases, is easily transmitted by 

 mechanical means, (birds, dogs, cats, etc.). Breaks like the last two are 

 easier to explain. Lack of annual 100 per cent testing is one of the inost 

 plausible explanations. 



The third flock presents another problem. The owner reported that for 

 the last two years an avian mixed infection bacterin has been used to 

 immunize the birds against chicken pox and winter colds. It is possible 

 that this product contained either a culture of the germ causing fowl 

 typhoid, or the one causing puUorum disease. In either case one would 

 expect to find reactors in the flock. This flock owner has been asked to 

 send some of the avian bacterin to the laboratory for examination, but 

 as yet has not done so. 



The fourth flock was non-reacting in 1927-28, but infected in 1928-29. 

 The c;uise of this break was easily traced to some new stock of another 

 breed added as hatching eggs, and hatched in the same incubator as his 

 original stock. This is another example of thoughtlessness on the part 

 of the poultryman. No doubt this poultryman has learned his lesson, 

 and next time will make a careful investigation of the record of the flock 

 from which he desires to purchase hatching eggs. 



Of the remaining 11 flocks, two were tested for the last time in 1926-27; 

 one in 1925-26; one in 1919-20; one in 1916-17; and six have been tested 

 for at least two consecutive years. None of the. 11 flocks has ever been 

 non-reacting, and no retesting within the season has been done; therefore, 

 is is not surprising that no better results have been obtained. 



Two of these flocks are of especial interest because in the spring of 

 1928, new stock was added from the same hatchery from which three 

 infected flocks, mentioned in the discussion of the 25 flocks tested for the 

 first time, came. Thus, five of the 40 flock owners having over 15 per 

 cent infection in their flocks bought the disease from one hatchery. This 

 hatchery is making every effort this year to furnish its customers with 

 stock from tested and non-reacting sources. Like other hatcheries operat- 

 ing in Massachusetts, it has found that pullorum disease-free chicks alone 

 f>re sought by the best poultrymen of this State. 



In the 51-60 per cent class is the flock of a young man who purchased 

 his entire stock, only nine birds, five of which reacted, from another state. 

 How much better off he would have been had he purchased his little flock 

 from his father who has the same breed and a flock disease-free for the 

 past three years. Besides losing a large percentage of his birds, he in- 

 troduced infection near where his father's stock is kept, which may be- 

 come a source of transmission of the disease to his father's stock. 



The one flock included in the group having over 60 per cent infection 

 originated from untested sources and 84.43 per cent were reactors. The 

 owner was advised to sell the 122 birds in the flock, and to buy replace- 

 ments from known tested and non-reacting sources. 



