Runting and leg weakness in broilers; Involvement of infectious factors

A syndrome characterized by runting, bad feathering and moderate to serious leg weakness occurring in broiler flocks could be reproduced experimentally in birds kept in isolators. The disease could be transmitted to one day old broiler chicks by inoculation of homogenized intestines from birds suffering from this syndrome. Moreover, the disease could be reproduced in a second bird passage with homogenized intestines collected 4 weeks after the primary inoculation. After inoculation of day old broilers with a bacterium and mycoplasma free filtrate of the original inoculum the disease occurred as well, but to a lesser extent. It is concluded that an infectious agent plays an important role in the etiology of this disease.