A study of the potential effect of dietary fishmeal replacement with cricket meal (Gryllus bimaculatus) on growth performance, blood health, liver antioxidant activities, intestinal microbiota and immune-related gene expression of juvenile channel catfish

Abstract

Studies have shown that insect meals can partially or completely replace fish meal (FM) that are commonly used in aquaculture. Therefore, a 10-week feeding trail was done to test the potential impacts of replacement of FM with cricket meal (CM) on the growth performance, body composition, blood health, liver antioxidant activities, intestinal microbiota and immune reaction of juvenile channel catfish. Five isonitrogenous (crude protein 35%) and isocaloric (19 MJ/kg−1) diets were formulated to have 0%, 25%, 50%,75% and 100% CM and named T0, T25, T50, T75 and T100 groups, respectively. Final body weight (FBW), weight gain rate (WGR) and specific growth rate (SGR) in fish fed T50 and T75 groups were considerably elevated compared with fish fed control T0 group. Higher hepatosomatic index (HSI) was found in fish fed T50, T75 and T100 groups compared with fish fed control T0 group. The moisture and crude protein contents in fish fed T75 and T100 groups were significantly increased than that of fish fed control T0 group. Hematological parameters examination of juvenile channel catfish demonstrated that hemoglobin (HGB), hematocrit (HCT), mean corpuscular hemoglobin (MCH) and mean corpuscular hemoglobin concentration (MCHC) showed significantly higher values with increasing content of CM in dietary fish fed groups. Malondialdehyde (MDA) content and glutathione peroxidase (GPx) activity level were highest in fish fed T75 group, respectively. Catalase (CAT) activity in fish fed T50 to T100 groups was significantly greater than those of fish fed control T0 and fish fed T25 groups. Intestinal microbiota sequencing analysis showed that Chao1, Shannon, Simpson indices, and Good’s coverage in fish fed control T0, fish fed T50 and T100 groups were not significantly affected. Intestinal microbiota analysis showed the relative abundance of Proteobacteria and Firmicutes were dominated at the phyla level. Moreover, with an increasing of CM replacement, the abundance of a prominent pathogenic bacterial Acinetobacter was reduced at the genus level although no significant differences. The immune-related gene expression levels of IL-1β, IL-8, IL-10 and HIF1α were up-regulated in intestine when CM replacement increased from 0% to 75%, and higher levels were observed in fish fed T75 group comparing to others. The expression levels of TNF-α, IL-22 and IFN-γ were significantly elevated in fish fed T100 group. Notably, fish fed T50 to T100 groups down-regulated the expression of NF-κB compared to the other groups. To conclude, the present findings show that CM could enhance growth performance, improving blood health and liver antioxidant capacity, and substantial alterations in intestinal microbial composition of juvenile channel catfish, suggesting that FM could be replaced by CM as insect protein source in channel catfish diet.