Serological monitoring of avian pathogens in layer farms using sentinel birds, 1: Mycoplasma gallisepticum, M. synoviae, Avibacterium paragallinarum, and Leucocytozoon caurelleryi

Specific-pathogen-free (SPF) chickens were housed with commercial laying hens in three layer farms as sentinel birds for 12 or 17 months to monitor Mycoplasma gallisepticum (MG), M. synoviae (MS), Avibacterium paragallinarum (APG) and Leucocytozoon caulleryi (Lc) infection. Antibodies against the above pathogens were examined, and egg production rates of layers were recorded. Antibodies to MG and MS were detected 20 days after introduction of sentinel birds in two farms where birds had been vaccinated against MG but not MS. Antibody to Lc was detected in two farms in early summer when egg-dropping occurred, and Lc was suspected as a causal agent for egg-dropping. Antibody to APG was not detected in any farm. These results suggest that SPF chickens may be useful for monitoring some avian pathogens in layer farms.