Role of Moringa oleifera leaves and aqueous extract in prevention of Motile Aeromonas Septicemia in common carp, Cyprinus carpio fingerlings with a reference to histopathological alterations

Abstract

Motile Aeromonas Septicemia (MAS) is a serious problem for fish farming industry. Attention has been focused on detecting novel products of plant origin for MAS prevention. Among these plants is Moringa oleifera that has a wide range of medicinal uses. The current study was carried out to evaluate the efficacy of dietary Moringa oleifera leaves (MOLs) and their aqueous extract in prevention of MAS in Cyprinus carpio fingerlings. Median lethal dose (LD50) of Aeromonas hydrophila was determined. Minimum inhibitory concentration, minimum bactericidal concentration, and agar well diffusion methods were used to determine antimicrobial activity of MOLs aqueous extract against Aeromonas hydrophila. Three different fish diets were prepared including diet1 with no additives (control), diet2 containing 1 g of MOLs/kg feed, and the third diet containing 10 ml of 10% MOLs aqueous extract/kg feed. Fish were fed with its specific diet at 5% of body weight for 30 days. At the end of the dietary experimental period, mortality and relative percent survival (RPS) were calculated. Organs were collected for histopathology. The LD50 was 1.5 × 105 CFU/ml. The aqueous extract exhibited excellent antimicrobial activity. No mortalities and 100% RPS were observed in all groups except 10% mortalities and 86 RPS of group fed MOLs then injected with Aeromonas hydrophila and 70% mortalities in control positive group. Severe histopathological alternations were observed in control positive group while that fed MOLs aqueous extract then injected with Aeromonas hydrophila showed normal histological structure of all examined organs. The group fed MOLs then injected with Aeromonas hydrophila showed mild histopathological changes in liver and kidney. Therefore, aqueous extract succeeded in prevention of MAS with no mortalities and no histological alterations. Further studies are needed for comparing between the traditional form of MOLs and their aqueous extract and their nanoparticle form in prevention of MAS disease in fish. Also, further studies are needed to explain the superior effect of MOLs aqueous extract in MAS prevention.