Black soldier fly, Hermetia illucens, larvae meal improves intestinal health and growth performance of Nile tilapia, Oreochromis niloticus, juveniles

This study investigated the effects of dietary black soldier fly (BSF) larvae, Hermetia illucens, meal on growth performance, feed utilization, intestinal health, and immune response in Nile tilapia, Oreochromis niloticus, juveniles. The fish (initial weight: 7.28 ± 0.09 g) were reared in a recirculatory aquaculture system (RAS) and fed diets containing different levels of defatted BSF larvae meal: 0% (control diet), 20% (BSF20), and 40% (BSF40). At the end of the feeding trial, the final body weight, weight gain, specific growth rate (SGR), protein efficiency ratio (PER), and feed conversion ratio (FCR) were significantly (p < 0.05) improved with increasing BSF meal inclusion levels in the diet. Histological analysis of the intestine revealed that mucosal fold length (MFL), muscularis thickness (MT), and goblet cell density (GCD) were significantly elevated by the BSF meal compared with the control. In addition, intraepithelial lymphocytes (IELs) and the enterocyte microvilli length were significantly elevated in BSF40-fed fish compared with the control. Gene expression analysis showed that intestinal chitin digestion-related (endochitinase A) and amino acid transporter (Slc6a18) genes were not significantly affected by the BSF meal. However, the expression of peptide transporter Slc15a1a was upregulated in the fish fed BSF40 compared to the control. Moreover, posterior intestine and head kidney cytokine (IL-1β, TNF-α, and IL-10) gene expression levels were not significantly affected by the inclusion of the BSF meal. Therefore, these results suggest that the BSF meal up to a 40% inclusion level can be used as an alternative protein source in the diets of Nile tilapia juveniles to promote growth and intestinal health.