Black soldier fly larvae (BSFL) meal is a high-protein, sustainable food that can partially replace costly conventional proteins in aquafeeds. However, its limited essential fatty acids warrant careful evaluation in broodstock diets, where fatty acids play pivotal roles in reproductive physiology. The effectiveness of partially defatted BSFL meal on gonadal maturation, steroidogenesis, and reproductive output in Clarias magur broodstock was examined in this 90-day feeding trial.
Four iso-nitrogenous (36% crude protein), iso-lipidic (8.5% lipid), and iso-caloric (374–386 Kcal DE/100 g) diets were formulates viz., T10 (10% BSFL inclusion), T20 (20% BSFL inclusion), and T30 (30% BSFL inclusion). There was a fixed low amount of fishmeal in every diet. In female broodstock, the hepatosomatic index (HSI) remained unchanged, but gonadosomatic index (GSI) increased significantly at 10% BSFL (T10) before declining at higher inclusions. Absolute fecundity did not differ significantly, yet relative fecundity and egg quality parameters were highest in the T10 diet. Fertilization rate, hatching rate, and larval survival improved significantly in T10 and T20 groups, whereas both control and T30 exhibited lower outcomes. In males, HSI decreased in BSFL-fed groups, while GSI increased up to 20% inclusion, indicating enhanced gonadal development. Hormonal assays demonstrated that estradiol was highest in the control, while 17α,20β-DHP and 11-ketotestosterone (11-KT) concentrations peaked in T10, followed by T20. In females, serum cholesterol levels decreased significantly in T10 and T20; similar patterns were noted in males, suggesting improved lipid mobilization and utilization. Reproductive gene expression analyses revealed unchanged FSHR expression in both sexes. In females, LHR expression increased significantly in T10 and T20, suggesting enhanced ovulatory potential.
This study demonstrates that partially defatted BSFL meal can replace soybean meal up to 20% in low fishmeal Magur broodstock diets, with 10% inclusion providing improved reproductive benefits.