This study evaluated survival, growth performance, digestive enzyme activities, intestinal histology, and antioxidant enzyme activities of the Pacific white shrimp (Litopenaeus vannamei), which were fed with five different diets, containing 0%, 25%, 50%, 75%, and 100% fresh black soldier fly larvae (BSFL), respectively, to replace commercial feed at an equal wet weight. The cultured experiment was lasted for 45 days, and the results showed that survival rate (SR), final body weight (FBW), and weight gain (WG) were negatively related with the replacement rate of fresh BSFL in the diet, where the maximum value was found in the BSFL 25% group, while the minimum value appeared in the BSFL 100% group. When BSFL replacement level was equal to or above 75%, the SR, FBW and WG were significantly decreased. However, hepatosomatic index (HSI) was increased with the increasing BSFL replacement level, which was significantly higher in BSFL 75% and BSFL 100% groups than the other groups. No significant differences on hepatopancreatic amylase and lipase activities of the shrimp were observed among all the groups. However, compared with the control group, protease activity in hepatopancreatic of the shrimp was significantly higher when up to 25% of commercial feed was replaced. The histological structure of the intestine gradually changed pathologically, such as tissue disruption, with increasing proportion of fresh BSFL in the diets. A significant reduction in intestinal fold height was found in the BSFL 100% group, and a decreased thickness of intestinal muscular was also observed in all treatment groups. The serum SOD and GSH-PX activities of shrimp in all treatment groups were significantly higher than that of the control group. In conclusion, replacing commercial feed up to 50% with fresh BSFL could be feasible for L. vannamei farming when growth performances, digestive enzyme activities, intestinal histology, and antioxidant enzymes were being considered.

This study investigated the effects of replacing commercial feeds with fresh black soldier fly larvae (BSFL) on the immune enzyme activities, water quality in the culturing environment, and intestinal microbiota of Pacific white shrimp (Litopenaeus vannamei). Five different feeding regimes were designed, in which 0% (control group), 25%, 50%, 75%, and 100% commercial feeds were replaced with equal wet weight of fresh BSFL, respectively. The experiment lasted for 45 days, and the results showed that the serum T-NOS (total nitric oxide synthase), AKP (alkaline phosphatase), and ACP (acid phosphatase) activity were significantly increased in the BSFL25% group. However, the immune enzymes of the hepatopancreas decreased significantly in all the BSFL-containing groups compared to the control group. Total ammonia nitrogen concentrations throughout the experimental phase and nitrate concentrations in the middle and later phases of the experiment were negatively correlated with the replacement rate of fresh BSFL in the diet, whereas pH was positively correlated with the replacement rate of fresh BSFL in the diet. Proteobacteria and Bacteroidetes were dominant phyla in the intestines of shrimps, but the relative abundances of Proteobacteria and Firmicutes decreased, with those of Bacteroidetes and Planctomycetes increased in the BSFL-containing groups. Among them, higher relative abundances of potential probiotics such as Motilimonas, Shimia, Pseudoalteromonas, and Shewanella and lower relative abundance of genus Vibrio were observed in the fresh BSFL-containing groups. Furthermore, shrimps fed with BSFL-containing diets had higher bacterial richness and diversity in the intestines. In conclusion, a proper replacement of commercial feed with fresh BSFL had a positive effects on the immune-related enzyme activities, water quality, and intestinal health in the L. vannamei.