The Effect of Fishmeal Replacement with Organic Acid Fermented Black Soldier Fly (hermetia Illucens) Larvae Meal on Growth, Nutrient Utilization, Metabolic Enzyme Activity, Antioxidant Status and Immunity in Pangasius (pangasianodon Hypophthalmus)

Black soldier fly (Hermetia illucens) larvae meal is emerging as an alternative protein source and good substitute of fishmeal (FM). In an 8 -week feeding trial, three hundred pangasius (Pangasianodon hypophthalmus,7.44 +/- 0.01 g) fingerlings were randomly allocated over five treatments in triplicate tanks and fed five isoprotein (CP, 35%) and isolipidic (CL, 10%) diets formulated by replacing 0% (FBSFL0), 25% (FBSFL25), 50% (FBSFL50), 75% (FBSFL75) and 100% (FBSFL100) FM with organic acid (formic acid) fermented black soldier fly larvae meal (FBSFL). The inclusion of FBSFL did not affect growth, feed conversion ratio, nutrients utilization and survival rate of pangasius even when FM was completely replaced. The pangasius body protein content increased significantly (P < 0.05) with increasing FBSFL level in the diets while, body lipid content was unaffected (P > 0.05). The haematological indices were not (P > 0.05) affected with the FBSFL inclusion levels. Significantly (P < 0.05) higher and alike protease activity was recorded in FBSFL50, FBSFL75, and FBSFL100 groups. However, activity of amylase and lipase were similar among treatments. The liver antioxidant enzymes (SOD, catalase, and GST) did not show significant (P > 0.05) difference among the treatments. However, pangasius fed with FBSFL75 and FBSFL100 showed significantly higher and similar total antioxidant capacity (T -AOC). The FBSFL in the diet of pangasius did not affect the liver metabolic enzyme (MDH, G-6-PDH and GDH) activities. Relative gene expression of growth hormone (GH1) did not substantially differ among the groups (P < 0.05). No differences were observed in the immune gene expressions of complement (C3) and interleukin-1 beta (IL-1 beta) but the expression level of transferrin was up -regulated significantly (P < 0.05) in FBSFL25 group. No damage was observed in hepatic tissues in histomorphometry examination due to the inclusion of FBSFL. The study concludes that formic acid fermented BSFL can be employed as a complete substitute for FM in the pangasius diet, offering additional health benefits without any adverse effects.