The study aimed to assess how replacing part of soybean meal protein with defatted Black Soldier Fly larvae (DBSFL) meal protein influences growth performance, leukocyte counts, biochemical parameters, immune response, and antioxidant levels in growing Muscovy ducks. A total of 100 one-week-old ducklings were randomly assigned to five groups, with four replicates of five ducklings each. The control group was fed the basal diet, while the experimental groups received diets in which soybean meal protein was partially replaced with DBSFL meal protein. The DBSFL meal levels used were 0%, 3.48%, 6.90%, 10.46%, and 13.95% of the total diet. The experiment lasted for 56 days. Growth performance was recorded weekly, and at the end of the experiment, three birds were randomly selected from each group, and blood samples were collected after slaughter. Serum was separated for biochemical parameters …