Levamisole enhances growth, haemato-biochemical indicators, resistance to Aeromonas veronii and expression of immune genes in asian seabass, Lates calcarifer

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.

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).

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<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.