Effects of Moringa oleifera ‐based diets on growth, immunological responses, liver antioxidant biomarkers and expression of immune‐related genes in Nile tilapia ( Oreochromis niloticus ) raised in hapa‐in‐pond system

Abstract

We have evaluated the impacts of supplementing diets with Moringa oleifera leaf extract (MOL) on growth, intestine histomorphometry, immunity, liver antioxidants and expression of immune genes in Nile tilapia raised in hapas mounted in earthen pond. Four MOL supplementation doses (0.0, 5.0, 7.0 and 9.0 g/kg) were used to make four experimental diets defined as reference (CONT), MOL5, MOL7 and MOL9 respectively. Fish (⁓61.5 g) were allocated in 4 triplicate groups and were fed the corresponding diets for consecutive 60 days. The highest final weight, weight gain, weight gain % and specific growth rate were found in the MOL5 group among all experimental groups. Feed conversion ratio was not changed by dietary MOL. When compared with the CONT group, there was a significant decline in MDA levels along with a significant rise in hepatic CAT, SOD and GPx enzymes in all MOL-supplemented groups. Serum lysozyme activities, IgM levels and complement C3 were elevated in MOL groups than the CONT group. Moreover, dietary MOL preserved the normal histomorphology of the intestines of the treated Nile tilapia along with a significant improvement in some intestinal morphometric indices. There was significant increase in the mRNA expressions of inf-γ, il-10 and tnf-α genes in the spleen tissue of MOL groups. However, the mRNA expression levels of il-1β were significantly decreased in MOL groups. Of interest, the second-order polynomial regression clarified that a 5.80 g MOL/kg diet is the optimum dietary supplementation level for better growth and no side effects on the health condition of fish. Altogether, dietary MOL could be recommended as a practical feed supplement to enhance growth, intestinal health, antioxidant capacity and immunity of Nile tilapia reared in hapas.