Used in immunological research to quantify complement protein 4 (C4) levels in duck serum or plasma samples. Helps in studying the activation of the complement system in avian immune responses. Supports research on infectious diseases, vaccine efficacy, and inflammatory conditions in poultry. Enables detection of C4 deficiencies or abnormalities linked to immune-related disorders in ducks. Widely used in veterinary diagnostics and avian immunology studies.