MORTALITY STUDIES IN R. I. REDS II 5 



CAUSES OF DEATH 



Facilities were such that the percentage of birds sent to the laboratory for 

 necropsy was far too low, and no necropsies were made on chicks thai died before 

 the age of eight weeks. The findings of the diagnostic laboratory are presented, 

 however, in the hope that they approximate a reasonable sample of disorders in 

 the flock. The same grouping of diseases and disorders employed in the first 

 report is made use of in Table 2. Since a bird may show more than one of these 

 disorders, the sum of percentages from left to right is often greater than 100. 



From Eight Weeks to Six Months of Age 



The control stock showed a high incidence of the leukosis complex during this 

 period. Kidney disorders appeared second in importance. Miscellaneous tumors, 

 reproductive disorders, miscellaneous disorders, and cannibalism each appeared 

 in about one bird out of seven examined. 



The high-mortality line exhibited a large amount of cannibalism and injuries 

 during the first two generations. No cases of the leukosis complex were dis- 

 covered in these birds. Miscellaneous tumors and kidney disorders were also 

 less frequent than in the controls. 



The low-mortality line was affected mainly by causes that were not specific; 

 also with parasites and cannibalism. No avian leukosis was discovered. 



From Six to Eighteen Months of Age 



The leukosis complex was somewhat more prevalent in the control line than in 

 either of the other lines. Control males had more cannibalism and a greater 

 number of miscellaneous disorders than any other abnormalties. The incidence 

 of the leukosis complex was much higher in females than in males. Cannibalism 

 was also very high in control females. 



In the high-mortality line there was little evidence that the leukosis complex 

 was very high. Cannibalism was prevalent in both males and females. There 

 was also evidence of considerable digestive trouble, and females had a significant 

 amount of reproductive disorders. 



The low-mortality line was freer from the leukosis complex than either of the 

 other lines. Cannibalism and miscellaneous disorders seemed to be rather 

 prevalent. 



In general, cannibalism in females and injury from fighting in males were 

 widespread. The two inbred lines appeared to be more affected by a considerable 

 array of disorders than was observed in the controls. 



