Effects of Moringa oleifera leaf extract on growth performance, physiological and immune response, and related immune gene expression of Macrobrachium rosenbergii with Vibrio anguillarum and ammonia stress

In order to study the effects of Moringa oleifera leaf extract on Macrobrachium rosenbergii under high ammonia exposure, freshwater prawns were randomly divided into five groups: a control group was fed with basal diet, and four treatment groups fed with basal diet supplemented with 0.25%, 0.5% and 1.0% M. oleifera leaf extract and 0.025% Enrofloxacin for 60 days, respectively. Then, freshwater prawns were exposed to high ammonia stress for 72 h and Vibro anguillarum infection. The growth, antioxidant capabilities, related immune genes as well as resistance to infection by V. anguillarum were determined. The results showed that compared with the control group, the weight gain, specific growth rate and protein efficiency rate, haemolymph catalase (CAT), superoxide dismutase (SOD) and inducible nitric oxide synthase (iNOS) increased while feed conversion ratio, haemolymph aspartate aminotransferase, alanine aminotransferase, nitrogen oxide (NO), hepatopancreas heat shock proteins (HSP70), immune deficiency (IMD) expression levels decreased in the group of 0.5% M. oleifera leaf extract before the stress. After ammonia stress, the group of 0.5% M. oleifera leaf extract also could improve the haemolymph SOD, glutathione peroxidase, NO, iNOS, hepatopancreas HSP70 expression levels and reduce haemolymph CAT, hepatopancreas peroxiredoxin 5 and NF kappa B inhibitor alpha expression level compared with the control group. The rate of mortality of the prawns challenged with V. anguillarum was lower in the supplemented groups in comparison with the control group with the lowest being in the group of 0.5% M. oleifera leaf extract. Antioxidant activities as well as biochemical parameters in the enrofloxacin group (0.025% E) were not significantly enhanced both pre and post challenge in comparison with the M. oleifera leaf extract groups, showing the superiority of the natural herb over the synthetic antibiotic. In summary, this study suggested that at an inclusion rate of 0.5%, M. oleifera leaf extract could increase the growth performance, even has positive effects on physiological and immune function and prevents high ammonia stress in the Freshwater prawn, M.rosenbergii.