Traditional Chinese herb formulas in diet enhance the non-specific immune responses of yellow catfish (Pelteobagrus fulvidraco) and resistance against Aeromonas hydrophila

Abstract

The effects of a traditional Chinese herbal mixture (TCHM) composed of Glycyrrhiza uralensis, Astragalus membranaceus, Rheum palmatum, Catsia tora and Lonicera japonica on immune response and disease resistance of yellow catfish (Pelteobagrus fulvidraco) were studied. Fish were fed diets containing 0% (control), 1.0%, 3.0% or 5.0% TCHM (w/w) for 28 d. Immune parameters including cytokine genes interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α) and Immunoglobulin M (IgM), acid phosphatase (ACP), alkaline phosphatase (AKP), lysozyme (LZM), catalase (CAT), superoxide dismutase (SOD) and immunoglobulin M (IgM) were measured during the test period. After 28 d of feeding, fish were infected with Aeromonas hydrophila, and mortality was recorded. The TCHM-supplementation diet stimulated ACP, AKP, LZM, CAT, SOD, and IgM activity in serum and induced IL-1β, TNF-α, and IgM mRNA expression in the spleen. All TCHM groups showed reduced mortality after A. hydrophila infection compared to the control group. These results suggest that the TCHM-supplemented diet can improve fish immunity and disease resistance against A. hydrophila.