In the human lower than normal concentrations of IgA in saliva have been found to be associated with stress. In studies of animal welfare and prolonged stress there is a need for nominvasive methods and assays of secretory IgA would be simple to develop for many species. In the present study we studied IgA in the chicken and compared levels of IgA in tears. serum and bile. Two strains of chickens were compared. The concentration of IgA in the lacrimal fluid of line C chickens was two-fold

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... than that of line 151 chickens. Levels of IgA in their serum and bile where the same. Following on from the replication of avirulent Newcastle disease virus (NDV)1n the Harderian gland of thc nietitating membiane line C chickens contained NDV — specific lacrimal IgA to a titre of 102 whereas line 151 chickens contained none at 10-1-5. Both lines conmined NDV ~specific IgA in their bile to a titre of 103. Line 151 chickens therefore have a selective deficiency in lacrimal IgA compared to biliary IgA.