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MASS. EXPERIMENT STATION BULLETIN No. 284 



Photograph 9. — Nine-day-old Chicks Free of Pullorum Disease. 

 Chicks I and II are males and 111 is a female. Refer to question 14. 



with white chalky excreta, marked depression and exhau.stion followed by 

 death. These symptoms are neither characteristic nor specific for pullorum 

 disease alone, since they may be observed in other health disturbances of chicks. 

 The mortality rate may vary from low to as high as 100 per cent. Losses may be 

 observed within two or three days after hatching and may continue until the 

 chicks are three weeks of age or older. The greatest losses usually occur during 

 the second week of chickhood. The onset and severity of the disease depend 

 upon the amount of infection in the body, the ability of the organism to produce 

 the disease, the resistance of the chick, and the care given by the poultryman. 

 In some cases diseased chicks show little or no evidence of infection, while in 

 other cases all the possible manifestations of the disease are found. 



Piiotojirapli 1(1. N'ine-day-old, Naturally Infected Pullorum Diseased Chicks. 

 .Shortened bodies, pastinft of the vents with excreta, droopiness and drowsiness are 

 symptoms aianifested by these chicks. Chick 111 died two days after it was photo- 

 graphed. .S. pullorum was isolated from chicks II and 111. C;hicks I and II are males and 

 III is a female. Refer to question 14. 



