Growth-promoting and immunostimulatory effects of phytobiotics as dietary supplements for Pangasianodon hypophthalmus fingerlings

Immunomodulatory, antioxidant, and growth-promoting activities of dietary fermented Moringa oleifera in Nile tilapia (Oreochromus niloticus) with in-vivo protection against Aeromonas hydrophila

BACKGROUND

Moringa oleifera, a well-known medicinal plant, has been used in aquafeed as a dietary supplement. Based on previous studies, insufficient research is available on the dietary supplementation of Nile tilapia with M. oleifera leaf and seed mixtures, specifically the fermented form. Therefore, this study aimed to investigate the efficacy of fermented (FMO) versus non-fermented M. oleifera (MO) leaf and seed mixtures on immunological parameters, antioxidant activity, growth performance, and resistance to A. hydrophila infection after a 30-day feeding trial on Nile tilapia.

METHODS

A total of 180 fingerlings were randomly divided into four groups in addition to the control group (36 fish each, in triplicate). Fish in the tested groups were fed on basal diet supplemented with MO5%, MO10%, FMO5%, and FMO10%, while those in control were fed on basal diet only. After the feeding trial, fish were challenged with A. hydrophila. The immunomodulatory activity of M. oleifera was evaluated in terms of phagocytic and lysozyme activities, immune-related cytokines and IgM gene expression. Antioxidants, and growth-promoting activities were also assessed.

RESULTS

The results revealed that fish supplemented FMO markedly in FMO10% group followed by FMO5%, exhibited significant (P < 0.05) improvement in the tested immunological, hepatic antioxidants, and growth performance parameters. Furthermore, the highest survival rate post-challenge with mild clinical symptoms, and the lowest A. hydrophila bacterial count were reported in these groups. Meanwhile, MO10%-supplementation exhibited the opposite trend.

CONCLUSIONS

The study' conclusion suggests that fermented M. oleifera leaf and seed mixture is a promising growth-promoting and immunostimulatory feed-additive candidate for Nile tilapia and could reduce the losses caused by A. hydrophila infection.

Effects of dietary walnut (Juglans regia) leaves extract on immunity, gene expression responses, and disease resistance in Oreochromis niloticus

The dietary effects of walnut leaf extract (WLE) on the growth, immunity, and resistance of Oreochromis niloticus to bacterial infection have been investigated. Five diets were prepared with various WLE doses of 0, 250, 500, 750, and 1000 mg/kg, termed as Con (control), WLE250, WLE500, WLE750, and WLE1000, respectively. Fish (11.67 ± 0.21 g) were fed these diets for 60 days and then challenged with Plesiomonas shigelloides. Before the challenge, it was observed that dietary WLE did not significantly affect the growth, blood proteins (globulin, albumin, and total protein), and liver function enzymes (ALT and AST) activities. The WLE250 group significantly increased serum SOD and CAT activities more than other groups. The serum immunological indices (lysozyme and myeloperoxidase activities) and hematological parameters (phagocytic activity %, phagocytic index, respiratory burst activity, and potential activity) were significantly increased in the WLE groups compared with the Con group. The expression of IgM heavy chain, IL-1β, and IL-8 genes were significantly upregulated in all WLE-supplemented groups in comparison with the Con group. The fish survival rates (SR; %) post challenge in the Con, WLE250, WLE500, WLE750 and WLE1000 groups were 40.0%, 49.3%, 86.7%, 73.3%, and 70.7%, respectively. The Kaplan-Meier survivorship curves illustrated that the highest SR% was found in the WLE500 group (86.7%) amongst the other groups. Accordingly, we can suggest that feeding O. niloticus with a diet supplied with WLE at a dose rate of 500 mg/kg over 60 days could enrich haemato-immune responses and increase the fish survival against the challenge with P. shigelloides. These results recommend using WLE as a herbal dietary supplement to substitute antibiotic use in aquafeed.