Dietary supplementation of fish protein hydrolysate improves growth, feed efficiency and immune response in freshwater carnivore fish, Channa striata fingerlings

The effect of dietary fish protein hydrolysate (FPH) at inclusion levels of 0% (control), 5% (FPH5), 10% (FPH10) and 15% (FPH15) (w/w) on growth, digestive enzyme activity, immune response and antioxidant status of striped murrel, Channa striata (4.18 +/- 0.04 g), was evaluated. The dietary FPH inclusion had significantly increased weight gain (WG), specific growth rate (SGR), protein efficiency ratio (PER) and decreased feed conversion ratio (FCR) compared with the control (p < 0.05). The specific activities of digestive enzymes (amylase and total protease) and transaminases (AST and ALT) were similar in all the treatment groups (p > 0.05). The inclusion of dietary FPH had no influence on SOD and NBT (p > 0.05). The antioxidant enzyme catalase was lower in the FPH5 group than in other treatment groups. Fish fed a diet supplemented with FPH had higher haemoglobin, WBC and albumin levels than the control group, indicating better health. The fish fed FPH10 displayed significantly improved serum lysozyme and myeloperoxidase compared with control, FPH5 and FPH15. Remarkably, qRT-PCR revealed significant upregulation of IGF-I in FPH10 and FPH15; complement component C3 in FPH10; and glutathione S-transferase (GST) in the fish fed FPH15 when compared to the control group. Based on the results of growth performance and immune response, it can be concluded that FPH at 10% may be recommended in the diet of striped murrel fingerlings.