Effects of chitin derived from black soldier fly larvae on growth performance, antioxidant capacity, hepatopancreas morphology, intestine microbiota, immune capacity, and lipid metabolism of Pacific white shrimp (Litopenaeus vannamei).

The use of polysaccharides as feed immunostimulants represents an effective alternative to antibiotics for disease prevention, with chitin emerging as a promising immune modulator. In this study, chitin was systematically extracted from black soldier fly (Hermetia illucens) larvae and incorporated into diets for Pacific white shrimp (Litopenaeus vannamei). Six experimental diets were formulated to contain graded levels of chitin: 0 (control, CD), 0.05%, 0.10%, 0.20%, 0.40%, and 0.80%, respectively. A total of 720 juvenile shrimp (0.32 ± 0.01 g, 6 weeks old) were equally allocated to the six dietary treatments (four replicates per group) and fed the respective diets for 56 d. The final body weight in the group supplemented with 0.20% chitin showed an increasing tendency compared with the control CD group (P = 0.056). Compared with the CD group, the relative mRNA expression level of cat in the hepatopancreas of Pacific white shrimp tended to be up-regulated in the 0.20% and 0.40% chitin-supplemented groups (P = 0.055); the activity of superoxide dismutase (SOD) in the hepatopancreas also significantly increased after the addition of 0.40% and 0.80% chitin (P = 0.006). Immunologically, a significant increase in the relative mRNA expression levels of dorsal and relish in the hepatopancreas was observed following the addition of 0.20% chitin compared with the CD group (P < 0.05). Regarding material metabolism, a decrease in serum glucose levels was observed when chitin was added at levels above 0.20% (P = 0.014); and it was observed a significant upregulation of irs, pi3k, s6k, srebp, and tor mRNA expression levels relative to the CD group (P < 0.05). A chitin-supplemented diet can enhance the antioxidant capacity, immune capability, lipid synthesis, and catabolism in Pacific white shrimp, without exerting negative effects on the morphology of the hepatopancreas and intestine microbiota. In the present study, the recommended inclusion level of the insect chitin to be added to the diets was 0.20%.