Used in immunological research to detect and quantify secretory immunoglobulin A (SIgA) in duck samples, particularly in studies related to mucosal immunity. Helps assess immune responses in the respiratory and gastrointestinal tracts of ducks, which is valuable in poultry health monitoring and vaccine development. Commonly applied in veterinary diagnostics and avian disease research, especially for pathogens like avian influenza and Newcastle disease virus. Enables researchers to evaluate the effectiveness of vaccines and the overall health status of duck populations in both commercial farming and experimental settings.