Multi-source protein complex - a potential fishmeal alternative in Pacific white shrimp (Penaeus vannamei): Responses in growth, physiology, and flesh quality

Abstract

This study evaluated a demand-driven protein complex formulated according to the nutritional requirements of Penaeus vannamei as a partial or complete replacement for fishmeal, and examined its effects on growth performance, body composition, immune and oxidative stress responses, tissue histology, and flesh quality. Data were analyzed using One-way ANOVA followed by Tukey's multiple comparison test. The protein complex, composed of hydrolyzed fish protein, Chlorella sp., and defatted black soldier fly larvae meal at a ratio of 4:3:3, represents a low-carbon, circular economy-oriented feed strategy. A total of 216 shrimp with an average initial weight of 3.50 g were randomly assigned to six treatments with three replicates each (12 shrimp/tank). Six experimental diets were formulated by replacing fishmeal at 0% (PC0, containing 300 g/kg fishmeal), 20% (PC20), 40% (PC40), 60% (PC60), 80% (PC80), and 100% (PC100), and a 56-day feeding trial was conducted. Growth performance did not differ significantly among treatments. However, shrimp fed the protein complex diets showed higher growth, with the PC80 treatment showing improved performance in weight gain (436.86%), SGR (3.00%/day), FCR (1.57), and PER (1.50). Whole-body crude protein content was significantly higher in the PC20-PC80 treatments than in PC0, while no reduction was observed in PC100, indicating that complete fishmeal replacement did not impair protein deposition. Immune and oxidative stress responses were not adversely affected by fishmeal replacement. Histological analyses confirmed that tissue structures remained intact across treatments. Texture profile analysis revealed increased hardness and gumminess in shrimp fed the protein complex diets (PC20-PC100), indicating enhanced flesh firmness. Overall, these results demonstrate that a multi-source protein complex based on amino acid complementarity can fully replace fishmeal without compromising growth performance, physiological stability, tissue structural integrity, or flesh quality, supporting the feasibility of a demand-driven protein system for sustainable shrimp aquafeeds.