This research evaluated the potential of black soldier fly larvae meal (BSFLM) as a partial substitute for soybean meal (SBM) in broiler diets, for their health and optimum performance. To this end, a total of 360 one-day-old male Cobb500 broiler chicks were randomly allocated to 36 floor pens and fed on basal starter (0-7 days) and grower (8-21 days) diets. During the finisher phase (22-35 days), chicks were randomly assigned to six treatment groups (six replicate pens of 10 birds per treatment) in which SBM was substituted with BSFLM at 0, 10, 20, 30, 40, or 50%, respectively. Growth performance traits were determined as pen averages for each treatment group (n=6). At the end of the trial, blood samples were randomly collected from two birds per replicate pen (n=12) to determine the plasma metabolites, antioxidant status, cytokine indices and immune responses. Additionally, jejunum and ceca specimens were obtained from two birds per replicate (n=12) to assess the jejunum histomorphology and cecal microbiota. Data was analysed through one-way ANOVA and Tukey’s post hoc test for comparison of mean differences. Results showed that including BSFLM up to 30% optimized feed conversion efficiency and maximized productive performance indices (P<0.05), including final BW (R²=0.724), BW gain (R²=0.729), and the European broiler index (R²=0.699). Intermediate inclusion levels (20-30%) were associated with alterations in the overall endocrine and physiological systems, characterized by higher thyroid activity (R²=0.608, P<0.001), enhanced antioxidant potential (R²=0.732, P<0.001) and lower pro-inflammatory cytokine interleukin-1b (R²=0.631, P<0.001). Immunological parameters, including leukocyte viability, antibody titers and lymphocyte proliferation, were also maximised at 20-30% replacement (R²=0.608-0.703, P<0.001). The intestines significantly (P≤0.001) exhibited better histomorphological features and a more balanced microbial composition in response to the 30% BSFLM treatment compared with other treatments. In conclusion, BSFLM can effectively substitute up to 30% of SBM in broiler finisher diets without adverse effects on productive performance and physiological status, offering a sustainable and effective protein alternative supplement for poultry production.

To Cite This Article: Abbas AO, Al-Suwailem NK, Alaqil AA, Assiri A, Gouda GF, Kamel NN, Ebeid TA, Safaa HM and Abdelwahab AAM, 2026. Substitution of soybean meal with black soldier fly (Hermetia illucens) larvae meal in broiler diets: comprehensive effects on growth, gut health and physiological resilience. Pak Vet J, 46(2): 312-320. http://dx.doi.org/10.29261/pakvetj/2026.023