Plant Ingredient diet supplemented with lecithin as fish meal and fish oil alternative affects growth performance, serum biochemical, lipid metabolism and growth-related gene expression in Nile tilapia

The current study evaluated the effects of replacing fish meal (FM) and fish oil (FO) with plant ingredients without or with lecithin supplementation on Nile tilapia growth, blood biochemistry, intestinal morphology, growth- and lipid-metabolism-related gene expression. Fingerlings were assigned to six dietary groups: FM and FO (G1), FM and plant oil (G2), plant protein and plant oil (G3), and the same three treatments but with lecithin supplementation (G4-G6) respectively. Fingerlings in G1 and G2 showed higher body weight than fish in G3 (p > 0.05). Lecithin supplementation improved (p < 0.05) growth, particularly in fish fed plant ingredients (G6). Fish fed different diets showed a significant increase (p < 0.05) in serum total cholesterol and low-density lipoprotein concentrations compared with G1. Albumin concentration was significantly reduced in G3 and G6. Partial or complete replacement of FO and FM with plant ingredients, with or without lecithin, significantly modulated (p < 0.05) expression levels of some regulatory genes related to growth and lipid metabolism, with the highest expression in lecithin-supplemented fish. It could be concluded that the complete replacement of FM and FO with plant ingredients (plant protein and oil) non-significantly reduced fish performance. Nevertheless, with lecithin supplementation, Nile tilapia can effectively utilize this plant-based diet as reflected with enhanced growth.