Hemolytic complement in specific-pathogen-free chickens: influence of age and sex

Six groups of specific-pathogen-free (SPF) chickens of various ages were tested for hemolytic complement (C) activity with a radial hemolytic diffusion technique. The chickens tested were 2, 6, 7, and 8 weeks old. Chickens 2 weeks old were found to have little hemolytic activity compared with chickens 6 to 8 weeks old. Mean titers were similar in the older chickens. No significant differences were found in C titers between males and females, unlike reports for mice.