Effect of dietary inclusion of gamma-ray irradiated black soldier fly larvae or grasshopper on blood metabolites and immunity in broiler chickens

This study aimed to evaluate the effects of replacing soybean meal with Black Soldier Fly Larvae (BSFL)/Grasshopper (GH) powders on health, mortality rate, blood metabolites, immune responses, and antioxidant enzyme activities in broiler chickens. A total of 546 male broiler chicks were randomly assigned to seven dietary treatments in a completely randomized design (n = 78 birds per treatment with 6 floor-pen replicates of 13 birds each). The control group was fed a conventional diet based on corn and soybean meal. In the test groups, soybean meal was progressively substituted with BSFL/GH powders at the levels of 8, 16, and 24 %. All insect meals used in the study were gamma-irradiated prior to inclusion The economic efficiency of the different dietary treatments was assessed using the European Production Efficiency Factor (EPEF). Broilers fed 24 % BSFL exhibited the highest EPEF across all growth phases (p < 0.05), with notable improvements also observed in birds receiving 16 % BSFL and 16-24 % GH. Mortality rates were lower in insect-fed groups than the control group. Diets containing BSFL significantly lowered serum cholesterol, triglycerides, and very low-density lipoprotein (VLDL) levels (p < 0.05). Immune responses, including antibody titers against Avian Influenza (AI), Newcastle Disease (ND), and Sheep Red Blood Cells (SRBC) on days 28 and 42, were significantly enhanced in birds receiving 24 % BSFL. White blood cell counts were not affected by dietary treatment (p > 0.05). Activities of antioxidant enzymes -glutathione peroxidase (GSH-Px), catalase (CAT), and superoxide dismutase (SOD)- and oxidative stress indicators including thiobarbituric acid reactive substances (TBARS) and total antioxidant capacity (TAC), remained unchanged (P > 0.05). These findings suggest that BSFL, and to a lesser extent GH, are promising, sustainable alternatives to soybean meal, enhancing broiler performance and immunity without compromising oxidative status. Gamma irradiation of insect meals may have contributed to these improvements. All insect meals were gamma-irradiated prior to inclusion; proximate composition and microbiological analyses indicated that irradiation did not compromise the nutritional quality of the insect meals. Further work should evaluate the long-term effects and commercial applicability of irradiated insect meals under commercial production conditions.