The Effect of Dietary Lipid Supplementation on the Serum Biochemistry, Antioxidant Responses, Initial Immunity, and mTOR Pathway of Juvenile Tilapia (Oreochromis niloticus)

Abstract

The objectives of this study were to investigate the effect of different dietary lipid levels on the serum biochemistry, antioxidant responses, initial immunity, and mTOR pathway of juvenile genetic improvement-farmed tilapia (GIFT, Oreochromis niloticus). Six groups of the juveniles (initial body weight 20.66 ± 1.33 g) in triplicate were fed for 90 days using six iso-nitrogen diets with different lipid levels (0.35%, 3.35%, 6.35%, 9.35%, 12.35%, and 15.35%). The main results were as follows: Compared with the control group (0.35%), the diets with different lipid supplementation significantly improved (p < 0.05) the contents of total protein (TP), albumin (ALB), globulin (GLB), glucose (GLU), triglyceride (TG), total cholesterol (T-CHO), high-density lipoprotein (HDL), low-density lipoprotein (LDL), total antioxidant capacity (T-AOC), malondialdehyde (MDA), complement 3 (C3), and immunoglobulin M (IgM), the activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), catalase (CAT), lysozyme (LYZ), and alkaline phosphatase (ALP), the expression level of phosphatidylinositol-3-kinase (PI3K), Akt protein kinase B (Akt), and mammalian target of rapamycin (mTOR) genes in juvenile tilapia. However, diets with different lipid supplementation significantly reduced (p < 0.05) the expression level of tumor necrosis factor α (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6) genes of juvenile tilapia. In conclusion, the with different lipid supplementation could significantly affect the serum biochemistry, antioxidant responses, initial immunity, and mTOR pathway of juvenile tilapia.