This study evaluated the effects of different treatments on the hematological profiles of ducks (Anas platyrhynchos) as indicators of physiological and immune responses. This study utilized 120 one-day-old male ducks assigned to eight treatments, and hematological parameters, including erythrocyte count, hemoglobin concentration, packed cell volume, total and differential leukocyte counts, total plasma protein, and fibrinogen, were analyzed. The results showed that erythrocyte counts (2.58–3.40 × 10⁶/µL), hemoglobin concentration (10.73–13.63 g/dL), and packed cell volume values (33.67–44.67%) remained within the normal physiological ranges, indicating no adverse effects on erythropoiesis or oxygen transport capacity. Total leukocyte counts varied among treatments (4.00–13.28 × 10³/µL), reflecting differences in immune responses. A progressive reduction in heterophil counts and stabilization of lymphocyte levels in the selected treatments suggested decreased physiological stress and improved immune balance. Total plasma protein values (4.20–5.70 g/dL) indicated adequate protein metabolism and hydration status, whereas lower fibrinogen concentrations in later treatments reflected reduced inflammatory responses. Overall, treatments that maintained stable erythrocyte indices, balanced leukocyte profiles, and low fibrinogen concentrations had favorable effects on duck health. These findings highlight the potential of probiotic-based interventions, particularly lactic acid bacteria (LAB) supplementation, in improving hematological stability and supporting sustainable duck production systems.