Effects of hirami lemon, Citrus depressa Hayata, leaf meal in diets on the immune response and disease resistance of juvenile barramundi, Lates calcarifer (bloch), against Aeromonas hydrophila

• Hirami lemon leaf meal improve barramundi immunity.
• Hirami lemon leaf meal improve barramundi disease resistance.
• Hirami lemon leaf meal improve an antiviral protein, Mx gene expression
• Four percentage of hirami lemon leaf meal is recommended in diet for barramundi aquaculture.

The present study was conducted to evaluate the dietary supplementation of leaf meal from Citrus depressa Hayata on the growth, innate immune response, and disease resistance of juvenile barramundi, Lates calcarifer. Four diets were formulated to contain 0% (control), 1% (C1), 3% (C3), and 5% (C5) leaf meal, respectively. During a 56 d feeding trial, fish survival, growth performance, and feed efficiency were not significantly different among all groups. For immune response, respiratory burst, superoxide dismutase and lysozyme activities were not significantly different among all groups. However, fish fed the C5 diet for 56 d had significantly higher phagocytic activity. Also, fish fed C3 and C5 diets had significantly higher Mx gene expressions in spleens and head kidneys with nerve necrosis virus injections after 24 h. Disease resistance against Aeromonas hydrophila was increased by the C5 diet. In this study, barramundi fed on a diet containing 5% C. depressa Hayata leaf meal had significantly better innate immune response and disease resistance against A. hydrophila.