The effects of Thai ginseng, Boesenbergia rotunda powder on mucosal and serum immunity, disease resistance, and growth performance of Nile tilapia (Oreochromis niloticus) fingerlings

The effects of Thai ginseng (TG), Boesenbergia rotunda, powder on some immune parameters in serum and skin mucus, resistance against pathogenic bacteria, Streptococcus agalactiae as well as growth performance in Nile tilapia, Oreochromis niloticus were studied. Experimental diets were prepared to contain 0 (D1), 5 (D2), 10 (D3), 20 (D4), or 40 (D5) g TG kg(-1) diet. Fish (17.29 +/- 0.11 g) were stocked in fifteen tanks (150 L; 20 specimen per tank) in triplicates for 8 weeks. Then, fish were challenged with pathogenic bacteria S. agalactiae. The results indicated that feeding with TG significantly enhanced lysozyme and peroxidase activities in tilapia skin mucus (P < .05), as well as serum lysozyme (SL), serum peroxidase (SP), alternative complement (ACH50), phagocytosis index (PI), and respiratory burst activities (RB). These enhancements were more evidenced in fish fed diets containing 10 g TG kg(-1) diet (P < .05). Similar increments were noticed in the immune parameters of fish with D3 treatment when compared with other treatment group (P < .05). Also, feeding on TG-supplemented diets were resulted in significantly elevated disease resistance in Nile tilapia against pathogenic bacteria, S. agalactiae, and highest survival of post-challenged fish was noticed in D3 treatment. Evaluation of growth performance revealed that TG supplementation to Nile tilapia significantly improved their final weight, weight gain, specific growth rate, feed intake, and feed conversion ratio (P < .05) with optimum TG level of 10 g kg(-1) diet. However, no significant differences in FI and survival rate (SR) were observed in fish fed TG and the control after 8 weeks post-feeding. These results demonstrated that dietary TG could be used as a beneficial feed additive aptimally at 10 g kg(-1) to improve performance and immune response of Nile tilapia.