| Abstrakt: |
This study aimed to manifest the dietary effect of Moringa oleifera(MO) leaf powder on growth performance and immunity in rainbow trout before and after Aeromonas hydrophilainfection. The fish (N = 360; 35.49 ± 0.50 g) were fed with incremental levels of MO at 0, 10, 25, and 50 g/kg for eight weeks and then challenged with A. hydrophilafor 10 days in triplicates. The final weight (114.6 g) and feed conversion ratio (1.28) were significantly decreased in MO-50 compared to other MO-added groups (P < 0.05). In the unchallenged fish, the total white blood cells (WBC), lymphocyte, and neutrophil population size did not change between the experimental and the control groups (P < 0.05), while after the bacterial infection, the number of circulating lymphocytes and WBC were significantly increased in both MO-25 and MO-50 groups compared to the control group. Before the challenge test, the expression level of lysozymegene in the head kidney was significantly (P < 0.05) increased in all MO-added groups, while the serum and skin mucus lysozyme, bactericidal, and complement activities were notably increased in MO-25 group. A similar trend was observed in the expression levels of IL-1βand TNF-1αgenes in the head kidney of MO-added groups, while the total mucus immunoglobulin and protein levels were elevated in both MO-25 and MO-50 groups. The expression levels of SOD, CAT,and GPxgenes were markedly down-regulated in MO-25 compared to the control group pre- and post-challenge test. The fish survival rate after challenging with A. hydrophilasignificantly increased from 46.7% in the control group to 76.7% in MO-25 group. In conclusion, using the supplemental diets with MO for rainbow trout at 19.3–25.0 and 27.5–30.5 g/kg is recommended based on the polynomial regression analyses to accelerate growth performance and provide immunostimulation, respectively. |
