Abstract / Description
The yellow mealworm (Tenebrio molitor) stands out among insect protein sources for its ability to convert low-value agricultural by-products into valuable nutrients. This study evaluated the effects of replacing fish meal with yellow mealworm meal on growth performance, nutritional composition, intestinal microbiota, hepatopancreas metabolites, and immune defense against decapod iridescent virus 1 (DIV1) in giant freshwater prawn. Five isonitrogenous and isolipidic diets were formulated with yellow mealworm meal replacing fish meal at 0% (FM30), 10% (FM27), 20% (FM24), 40% (FM18), and 60% (FM12). A total of 750 prawns were randomly distributed into 15 tanks (three replicates per diet, 50 prawns per replicate) and cultured for 56 days, followed by a DIV1 challenge test. Results showed that Replacement of up to 60% of fish meal did not adversely affect growth performance, feed utilization, or the crude protein, crude lipid, and amino acid profiles in muscle. Muscle monounsaturated fatty acids (MUFAs) increased linearly with mealworm inclusion (p < 0.05). The FM12 group exhibited elevated arachidonic acid (ARA) and n-6 PUFA levels and reduced docosahexaenoic acid (DHA; p < 0.05), while the n-3/n-6 ratio remained unchanged. Gut microbiota composition shifted favorably, with increased abundance of Firmicutes and beneficial Lactococcus in the FM12 and FM18 groups (p < 0.05). Metabolic adaptation in the hepatopancreas involved glycerophospholipid metabolism, nucleotide metabolism, and pyruvate metabolism pathways. Following DIV1 challenge, the FM12 group showed significantly higher survival, increased plasma glutathione peroxidase (GPX) activity, decreased malondialdehyde (MDA) levels, and reduced hepatopancreatic apoptosis (p < 0.05). Immune-related upregulation of hpo, warts, mats, and ifn-α, alongside downregulation of caspase-3, was also observed (p < 0.05). In conclusion, replacing 60% of dietary fish meal with yellow mealworm meal is a nutritionally safe and beneficial strategy for giant freshwater prawn, effectively maintaining growth performance and muscle composition, modulating gut microbiota, and enhancing immune defense against DIV1.