Pomegranate peel and moringa-based diets enhanced biochemical and immune parameters of Nile tilapia against bacterial infection by Aeromonas hydrophila.

We previously reported that Aeromonas hydrophila exhibited the highest prevalence rate amongst 182 bacterial strains isolated from naturally diseased Nile tilapia (Oreochromis niloticus) collected from El-Abassa Fish Farm, Egypt (Hassan et al., Egypt. J. Aquac., 10, 23-43, 2020). The overuse of antibiotics for controlling diseases has led to acquired antibiotics resistance of aquatic bacteria, besides the developments of human, aquatic animal and environmental risks arising from residual antibiotics. Therefore, the evaluation of safe alternative phytotherapies is of great importance. This study was conducted to evaluate and compare growth performance and immune potentiating activities of moringa (Moringa oleifera) leaves extract (Moringa LE) and pomegranate (Punica granatum) peel extract (Pomegranate PE) on Nile tilapia against infection with a pathogenic bacterium, Aeromonas hydrophila. A total of 150 Oreochromis niloticus were randomly divided into 5 groups to be fed at 3% of body weight with isonitrogenous/isoenergetic diets supplemented with Moringa LE at 0.15 and 0.25% kg or Pomegranate PE at of 0.3 and 0.5% kg, separately. Growth performance was significantly affected by Moringa LE as compared with the control group without supplementation of plant extract, while Pomegranate PE levels did not affect growth performance. Maximum average daily gains, specific growth rate, albumin, globulin, total protein, A/G ratio, alanine amino transaminase (ALT), aspartate amino transaminase (AST), cholesterol, triglyceride, creatinine, urea, and lysozyme were analyzed. Antioxidant enzymes of catalase and superoxide dismutase were also evaluated in liver tissues. After feeding experiment, the results indicated that the addition of Moringa LE and Pomegranate PE improved lipid profile, liver and kidney functions, immune response towards the emerging bacterial diseases. Besides this, feeding the fishes on diets supplemented with Moringa LE at concentration 0.25% kg showed the best growth performance, and improved immunity. Moreover, it exhibited the highest protection against bacterial infection with Aeromonas hydrophila achieving the lowest mortality rate of 10% as compared to 80% of mortality rate at the control group.