Modulation of acute stress and immune response in tilapia, Oreochromis niloticus, using longevity spinach, Gynura...

We investigated the effects of different concentrations of longevity spinach, Gynura procumbens, on the hematological parameters of acutely stressed Nile tilapia, Oreochromis niloticus, (average weight 461.81 ± 16.60 g and average length 28.71 ± 0.34 cm) and determined the best concentration. The fish were subjected to hormonal stress in this research. We fed the stress control group commercial feed with 0.01% hydrocortisone, a stress hormone (0.01% of fish body weight) without Gynura. All the treatment groups were supplemented with Gynura extracts (0.5 g/kg, 1.0 g/kg, and 1.5 g/kg of feed weight) in combination with hydrocortisone. We evaluated blood glucose, lysozyme activity, phagocytic capacity, hematocrit, spleen somatic index, and hepatosomatic index. During the acute stress period, G. procumbens has been shown to decrease the levels of blood glucose in 1.5 g/kg treatment group (49.60 mg/dl at Day 1; 53.75 mg/dl at Day 3) compared to stress control group (80.00 mg/dl at Day 1; 69.20 mg/dl at Day 3). Higher lysozyme activity observed in 1.5 g/kg Gynura treatment group (11.44 T/min at 540 nm) compared to control (7.85 T/min at 540 nm). The 1.5 g/kg treatment group maintained the homeostatic level of significant physiological parameters including phagocytic capacity, packed cell volume, and hepatosomatic index. These findings are promising for the development of new nutraceuticals for the aquaculture industry.