The high lipid content of full-fat or partially defatted black soldier fly larvae (BSFL) meal limit its digestibility and nutrient utilization in the early life stages of shrimps. However, the hydrolyzed form of BSFL provides readily available nutrients and bioactive peptides that can promote growth and well-being. Hence, beyond serving as a fishmeal replacer, the present study attempted to understand the potential of enzyme hydrolysed BSFL meal as a functional ingredient supporting gut integrity and physiological performance.
Thirteen optimization trials were carried out to establish an efficient hydrolysate preparation protocol. A two-step enzymatic hydrolysis using 2% papain and 2% lipase for two hours resulted in 88.67% dry matter recovery, 64.57% protein content, and 5.35% chitin, indicating a high-quality protein hydrolysate suitable for feed application. Five isonitrogenous (36% crude protein) and isolipidic (9% crude lipid) diets were formulated by incorporating graded levels of BSFL hydrolysate (0%, 4.06%, 8.12%, 12.18%, and 16.24%), replacing fishmeal at 25%, 50%, 75%, and 100% levels for a 60-day feeding trial.
Results revealed that shrimp fed the diet containing 8.12% BSFL hydrolysate (T2) achieved significantly higher (p < 0.05) final weight, weight gain, daily weight gain, and specific growth rate, along with the lowest feed conversion ratio. Elevated protease and lipase activities and higher gut microbial diversity, indicated superior nutrient utilization in T2. Antioxidant enzyme activities (SOD, catalase) and survival did not differ significantly among treatments. Immune gene expression showed upregulation of penaeidin, lysozyme, and HSPs in the hydrolysate-fed groups, reflecting improved immune responsiveness and cellular protection. Histological examination confirmed intact hepatopancreatic structures in all treatments. Overall, dietary inclusion of 8.12% BSFL hydrolysate significantly enhanced growth and immunity in vannamei.