Dietary Supplementation of the Rainbow Trout, Oncorhynchus mykiss by Red Ginseng, Panax Ginseng" Powder: Enhancing Effects on Growth, Immunity and Disease Resistance.

This study aimed to determine the effects of dietary red ginseng, Panax ginseng powder (RGP), on the growth performance, immunity, antioxidant system, and disease resistance of the rainbow trout, Oncorhynchus mykiss. Eight experimental groups were established, including a control group and seven groups fed varying levels of ginseng powder (5 to 35 g/kg) over 60 days, followed by a challenge with Streptococcus iniae. The results indicated that ginseng supplementation significantly enhanced growth parameters (P < 0.01), with the final weight (FW) of fish in the RGP₆ (fish fed 25 g/kg RGP) group reaching 56.7 g, compared to only 36.2 g in the control group (P < 0.01). Weight gain percentages (WG%), specific growth rates (SGR), and feed conversion ratios (FCR) also improved markedly in the RGP-fed groups (P < 0.01). Furthermore, Amylase, trypsin, chymotrypsin, and lipase activities increased with higher RGP levels, particularly in the RGP₇ (fish fed 30 g/kg RGP) group (P < 0.01). Immune parameters in serum, including lysozyme, complement activity (ACH₅₀), total Ig, and myeloperoxidase activity (MPO), demonstrated significant enhancements, especially in RGP₆ and RGP₇ (P < 0.01). Mucus immune responses were also improved by the dietary RGP. The highest total Ig, alkaline phosphatase, protease, and lysozyme activities in mucus were observed in the RGP₇ group (P < 0.01). The antioxidant enzyme activities, including superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx), also showed significant increases with RGP supplementation(P < 0.01). Liver enzyme activities decreased with higher RGP levels, particularly in the RGP₇ group (P < 0.01). Malondialdehyde (MDA) levels, were significantly lower in the RGP-treated groups compared to the control (P < 0.01). Control group exhibited the highest mortality after bacterial challenge, while groups RGP₆ and RGP₇ showed significantly lower mortality rates. Overall, the findings underscore the potential of RGP as a dietary supplement to enhance growth, immunity, antioxidant activity, and disease resistance in the rainbow trout, offering promising implications for aquaculture practices.