Serological investigations of a bovine respiratory disease ("urner pneumonie") resembling farmer's lung.

The immunological response of cattle exposed to moldy hay was examined by agar gel diffusion with standard farmer's lung hay antigens. A high incidence of precipitins against Micropolyspora faeni (60%) and moldy hay antigen (80%) was detected in exposed but apparently healthy cattle from a region with a high incidence of bovine farmer's lung. In comparison, in the plains, a low incidence area, we found only 1 animal of 164 harboring precipitins against M. faeni. We further observed that many animals from exposed populations lost their precipitins during pasturing and regained them during winter housing. Thirty-nine clinical cases of bovine farmer's lung ("Urner Pneumonie") were investigated serologically. Only 49% of these animals showed precipitins against M. faeni and 54% showed precipitins against moldy hay antigen. We discuss in this paper the probable causes of this apparent lack of immunological response.