Application evaluation of black soldier fly (Hermetia illucens) larvae oil in shrimp feed: Effects on growth performance, antioxidant capacity and lipid metabolism

Recently, the global supply shortage of fish oil (FO) has resulted in rapid price increases, and aquatic feed is the largest consumption of FO. Black soldier fly larvae oil (Hermetia illucens) (HIO) is rich in lauric acid and has been suggested as a possible source of lipids for the aquatic diet. The current study aims to evaluate whether it is feasible to replace FO in Pacific white shrimp (Litopenaeus vannamei) (4.95 ± 0.10 g) with HIO and to investigate the effects of this substitution on growth, biochemical indices, approximately composition, expression of genes related to the immune, lipid metabolism, and antioxidant response. Five diets were formulated, which contained different replacements of FO with HIO; the substitution percentages were as follows: 0 %, 25 %, 50 %, 75 % and 100 %, respectively. The results indicated that PWG was improved when substitution percentage was less than 75 %; however, when substitution percentage was more than 50 %, the PWG decreased significantly. The lipid content of the hepatopancreas, muscle and whole body was markedly affected by substitution percentage. The fatty acid composition of hepatopancreas was positively relevant to that in the diets, and the lauric acid content was significantly elevated with the increment of HIO instead of FO in diets. The expression of lipid-related synthesis significantly increased at HIO100, and the lipolysis genes showed an upward trend. Substitution percentage has a significant impact on the expression of fatty acid transport. The proportion of FO replaced by HIO was increased from 0 % to 100 %, and the mRNA expression of immune-related genes was significantly upregulated. Moreover, the increased substitution percentage significantly increased the activities of hemolymph ACP, PPO and T-NOS. In summary, the effect of PWG on the replacement of HIO by FO in feed was analysed according to quadratic regression analysis, the optimal replacement levels were estimated to be 34.92 %.