Effect of phytogenic feed additive (Digestarom PEP) on growth performance, hematological parameters, immunity system, and carcass quality of giant gourami (Osphronemus goramy)

There is a growing interest among researchers to use herbal supplementations in aquafeed to enhance growth performance as well as the immunity systems of aquatic animals. Therefore, this study was conducted to investigate the effect of phytogenic feed additive (Digestarom PEP) on growth performance, chemical composition, hematological and immune responses of giant gourami (Osphronemus goramy). For this purpose, giant gourami with the average weight 3.1±0.2 g with selective experimental treatments included, control (0 g Digestarom PEP/kg), T1 PEP 0.5% (5 g Digestarom PEP/kg), T2 PEP 1% (10 g Digestarom PEP/kg), and T3 PEP 1.5% (15 g Digestarom PEP/kg) were feed for 60 days. Based on the growth performance results, a significant difference was observed in the specific growth rate (3.19 %/day), weight gain (18.47 g), and feed conversion factor (0.78) of PEP 1.5% treatment compared to other treatments (p<0.05). Based on the hematological results, there was a significant difference in the red and white blood cells numbers, neutrophil and monocyte percentages, and hematocrit level in PEP 1.5% treatment compared to other treatments (p <0.05). The levels of immune indices including lysozyme activity, IgM, complement proteins (C3 and C4) were significantly increased (p<0.05) in PEP 1.5% treatment compared to others, especially the control one. Also, there was a significant difference in the crude protein (15.37%) and lipid (3.87%) contents among PEP 1% and PEP 1.5% compared to control and PEP 0.5% (p<0.05). In conclusion, the results of this study showed that dietary administration of Digestrom™ PEP, especially at 1.5% concentration, could improve growth performance and innate immune responses of giant gourami.