Effects of Dietary Supplementation of Euphorbia hirta on the Growth Performance, Serum Biochemistry, Antioxidative Status, and Immune Response of Clarias gariepinus

The medicinal herb Euphorbia hirta is abundantly available and exhibits impressive biological properties. This study looked at how dietary E. hirta extract (EHE) affected Clarias gariepinus growth, biochemistry, antioxidant status, immunological response, and resistance to Aeromonas hydrophila (AE) infection. Five isonitrogenous diets of 40% crude protein were prepared to contain 0.0, 0.5, 1.0, 1.5, or 2.0 g EHE/kg feed. Fish (n = 450; mean = 6.60 g) were randomly distributed to 15 500-L aquaria (30 fish/aquarium; 100 cm × 100 cm × 60 cm, length × width × height) and fed thrice (07:00, 12:00, and 17:00 h) daily with experimental diets for 12 weeks until apparent satiation. Fish guts and blood samples were taken from the fish to measure antioxidant parameters, serum biochemical parameters, and intestinal morphometry. After the feeding trial, the fish received an intraperitoneal injection of pathogenic AE and were monitored for 14 days. Blood samples were taken for the immune response testing following the 14-day challenge test. With a 0.5 g/kg diet, dietary EHE improved weight gain (WG), specific growth rate (SGR), villi height, and FCR. Blood proteins, urea nitrogen, and creatinine were unaffected, although alkaline phosphatase (ALP) concentrations appeared to decrease as the EHE inclusion levels increased. Fish-fed EHE-based diets showed increased activity of the serum antioxidant enzymes glutathione (GSH)-s-transferase (GST),GSH peroxidase (GPx), and superoxide dismutase (SOD). In the challenged fish-fed EHE-supplemented diets, respiratory burst, and lysozyme activity were increased, with the highest relative survival (RS) occurring at 0.5 g EHE/kg diet. In conclusion, this study found that 0.5 g EHE has growth-promoting, antioxidant, and immune-stimulating effects in C. gariepinus against AE infection, hence its inclusion at this level is advised.