PULLORUM DISEASE 



27 



to chicks that are hatched from eggs selected from pullorum-free flocks. In some 

 sections many hatcherymen do not appreciate this fact. 



74. If new stock is desired, what kind should be selected? In selecting new 

 stock, the first consideration is health. Adults, chicks, and eggs should be selected 

 that are free from infection. Such stock may be obtained from recognized pul- 

 lorum disease-free flocks. 



NLw ELngland Breeolr-HatchersFarm Plan 

 Facilitates Pullorum Disease Eradication 



Midwes'tern Hatchery^ Plan or Operation 

 IN Pullorum Di&EASEt3oNTRoi_ 



Pullorum Status of Farm Flocks 



ni ChiCK RiPUCEMEN 

 FOR OloStO' 



Figure 27. Left: Schematic illustration of breeder-hatcher plant such as is common in the 

 New England States. Pullorum-clean breeding stock, puUorum-clean eggs, and progeny all 

 carefully managed by the owner, the breeder-hatcher. 



Right: Schematic illustration of reproducing chicks in some sections of this Country. This 

 hatchery selects eggs from various tested supply flocks, some negative and some posUive, with 

 the result that the negative supply flocks are replaced by infected progeny. 



75. Are tested flocks officially classified? Yes. The National Poultry Improve- 

 ment Plan has established four classes in pullorum control and eradication: 

 U. S. Pullorum-Tested, U. S. Pullorum-Controlled, U. S. Pullorum-Passed, and 

 U. S. Pullorum-Clean. 



76. What is a U. S. Pullorum-Tested flock? A flock in which all chickens to 

 be used as breeders have been tested for pullorum disease when more than five 

 months of age, under the supervision of an official State agency. The percentages 

 of tolerance of reactors specified in this grade are as follows: fewer than 9 per- 

 cent in 1941-42, fewer than 8 percent in 1942-43, fewer than 7 percent in 1943-44, 

 fewer than 6 percent in 1944-45, and fewer than 5 percent in 1945-46 and the 

 following years. In each instance the last test must have been made within the 

 12 months immediately preceding the date of sale ot hatching eggs or chicks from 

 such flocks. 



77. What is a U. S. Pullorum-Tested hatchery? One operating under the 

 supervision of an official State agency and hatching eggs or brooding chicks from 

 only U. S. Pullorum-Tested, U. S. Pullorum-Controlled, U. S. Pullorum-Passed, 

 or U. S. Pullorum-Clean flocks; except that custom hatching for non-U. S. Pul- 

 lorum-Tested flocks is permitted, provided certain stipulations as to the number 

 and location of the incubators and the construction of the hatchery are observed. 



78. What is a U. S. Pullorum-Controlled flock? A flock in which all chickens 

 to be used as breeders have been tested for pullorum disease when more than five 

 months of age, under the supervision of an official State agency, and which con- 



