12 



Of tlie 33 flocks having previous testing history, all but three were 

 tested in 1927-28. Nineteen were 100 per cent tested, while 14< were less 

 than 100 per cent tested in 1928-29. The results of retesting during the 

 1928-29 season formed the basis for classification of 13 flocks in this 

 group. Two of these 13 flocks had between 10 and 20 per cent infection 

 on the original test; live had be"tween 6 and 10 per cent; and six had from 

 1 to 5 per cent. With the exception of one flock, only one retest was 

 made. 



Eight of the 33 flocks with previous testing history were non-reacting 

 in 1927-28. One of these was only partially tested during the last season, 

 and is located within a few yards of a flock which has had a large per- 

 centage of infection for two years. The second was partially tested in 

 1928-29, and had not been tested previously since 1925-26. The third 

 flock was non-reacting on the first retest in 1927-28. With the exception of 

 a few, all reactors were among the birds which were hatched previous to 

 the time of the original test in 1927-28. Infection in the fourth flock 

 can probably be accounted for by the introduction, after the previous 

 tests, of Barred Rocks from a source known to be infected. The Rhode 

 Island Reds in the flock were witliout infection, while the Barred Rocks 

 had 2.74 i^er cent infection. 



The fifth flock was non-reacting in 1927-28, but two reactors were 

 found in one pen in the past season's test. Both of these reactors were 

 sent to the Iaborator\' and the causative organism was isolated from each. 

 The reason for infection getting into the flock was not determined. This 

 i? another example of the need for annual 100 per cent flock testing. If 

 this man had tested all of the birds with the exception of the one pen 

 he would have considered his flock disease-free, and the two reactors might 

 have been responsible for a large loss among the chicks, as well as a 

 large percentage of infection in his flock in the 1929-30 test. 



The sixth flock was owned by a man who had three Brahmas from an 

 unknown source on his premises. The only reactor was one of the three 

 Brahmas. In the seventh flock, the infection was probably introduced 

 through an incubator where custom hatching was carried on. At least 

 one other flock, which was previously negative, became infected by this 

 same incubator. The eighth flock having a non-reacting report the pre- 

 vious season, was one for which no history has been obtained, except that 

 various blood collectors report poor cooperation and poor management. 

 In such instances it is not surprising that an infectious disease finds its 

 way into the plant. 



Thirteen of the flocks having previous testing history were only partial- 

 ly tested at their last test, and ten of these were in the group of 14 which 

 were less than 100 per cent tested in 1928-29. 



One to Five Per Cent Infection 



There were 49 flocks which had from 1 to 5 per cent infection. Twenty 

 were tested for the first time, and 29 had previous testing histories. 



In the group which were tested for the first time, 14 were 100 

 per cent tested, and six were less than 100 per cent tested. The histories 

 of these flocks are not different from those in the other classes where more 

 infection M'as found and which are discussed later. All but one flock in 

 the group originated from either unknown, infected, or a combination of 

 unknown, infected, and non-infected flocks. Ten of the group originated 



