Levamisole Enhances Growth, Haemato-biochemical Indicators, Resistance to Aeromonas veronii and Expression of Immune Genes in Asian Seabass, Lates calcarifer

Background: The objective of this study was to assess the effects of dietary levamisole supplementation feed on the growth, hemato-biochemical parameters, disease resistance and the expression of genes related to growth and immunity in Asian seabass, Lates calcarifer. Methods: Triplicate groups of fish (n=20) with an average weight of 3.29±0.4 g were fed with feed supplemented with levamisole (C, 0.0 mg/Kg; LVT1, 75 mg/Kg; LVT2, 150 mg/Kg; LVT3, 300 mg/Kg; LVT4, 600 mg/Kg) for 60 days. At the end of the experiment growth, haemato-biochemical parameters and disease resistance to Aeromonas veronii were assessed. Relative expressions of growth and immune genes were analyzed by quantitative real-time PCR (qPCR). Result: Dietary incorporation with levamisole in the range of 75 – 600 mg/Kg diet improved the haemato-biochemical indices, survival rates and resistance to Aeromonas veronii challenge (CAK4/SRLAAH/2022) at a concentration of 2.5 ´ 104 cfu/ml. Levamisole incorporation at 300 mg/Kg feed (LVT3) resulted in significant (p less than 0.05) improvements in various parameters such as feed efficiency, growth rate, increased disease resistance and upregulated expression of both growth and immune-related genes in comparison to the control (C). Significant improvements in haemato-biochemical indices such as hemoglobin (Hb), white blood cells (WBC), packed cell volume (PCV), erythrocytes (Ery), glucose (GLU), cholesterol (Cho) and triglyceride (TG) levels were also recorded.