Substituting fishmeal with Hermetia illucens in the diets of African catfish (Clarias gariepinus): Effects on growth, nutrient utilization, haemato-physiological response, and oxidative stress biomarker

Abstract

A 60-day experiment was conducted to examine the effect of fishmeal substitution with black soldier fly larvae (BSFL) meal on the growth performance, nutrient utilization, haematology, serum biochemistry, and oxidative status of Clarias gariepinus fingerlings. Four diets were formulated to be isonitrogenous (418 g Kg−1 crude protein), isolipidic (95 g Kg−1 crude lipid) and isocaloric (20.14 MJ Kg−1 gross energy). The control diet was formulated using fishmeal (FM) as the principal protein source and was progressively substituted with Hermetia illucens (hereafter referred to as HP) larvae meal at 25%, 50%, and 75%, on equivalent protein basis, corresponding to dietary inclusion level of 57, 115, and 172 g Kg−1, respectively. A total of 180 fingerlings of African catfish (Clarias gariepinus) was used for the trial and distributed randomly to twelve plastic tanks each containing 15 (4.0 ± 0.01 g/fish) fish. At the end of the trial, the fish fed HP 50% recorded the highest final body weight, weight gain, weight gain percentage, and specific growth rate compared to other groups (p < .05). The nutrient utilization indices such as feed conversion ratio, protein efficiency ratio, and protein productive value were found to be better in fish fed HP 50% compared with the control but no significant effect (p > .05) was noticed on the feed intake. A significantly higher whole-body protein was recorded in HP 50%, whereas lipid and ash contents showed no variation (p > .05). The blood parameters and differential leucocyte counts were not statistically different; however, serum total protein, globulin, glucose, triglycerides, and total bilirubin differed significantly among the dietary groups (p < .05). The liver function enzyme (AST and ALT) showed that the fish fed HP 50% recorded the lowest value. The results of the oxidative stress biomarker indicate that the fish fed HP-based diet had similar malondialdehyde (MDA) content with the control, but the superoxide dismutase and catalase enzyme activities were found to be higher in the control and HP 50%, respectively. Summarily, the results of the current study showed that African catfish can effectively utilize Hermetia illucens up to 172 g Kg−1 (75% FM replacement) without impairing growth, nutrient utilization, antioxidant, and health status of the fish.