Dietary lipid levels could improve growth and intestinal microbiota of juvenile swimming crab, Portunus trituberculatus

An 8 week feeding trial was conducted to evaluate the effects of dietary lipid levels on growth and intestinal microbiota of juvenile swimming crab. Three isonitrogenous (47% crude protein) diets were formulated to contain 5.8%, 9.9% and 15.1% crude lipid levels, respectively. Three groups of swimming crab (n = 60 per group) were randomly assigned to each diet. An Illumina-based sequencing method was used to analyze the intestinal bacterial composition of the crabs. The results indicated that swimming crab fed the diets containing 5.8% and 9.9% lipid had significantly higher weight gain and survival than those fed the 15.1% lipid diet. Proteobacteria, Fusobacteria and Tenericutes were dominant in the intestines of swimming crab regardless of the diet; the relative abundance of Fusobacteria decreased while Proteobacteria increased with increase of dietary lipid levels. Swimming crab fed the diets containing 9.9% and 15.1% lipid had a higher abundance of pathogenic bacteria than those fed the 5.8% lipid diet. These results indicate that dietary lipid levels could affect the composition of the intestinal microbiota; also, higher dietary lipid levels have a negative impact and increase the potential risk of disease in swimming crab.