Abstract
A feeding trial was conducted for 120 days in a pilot field condition to evaluate ginger powder (GP; Zingiber officinale) as a feed supplement for Labeo rohita to improve immunity, blood metabolic profile, and resistance to Aeromonas hydrophila bacterial infection. The study was conducted following a complete randomized design in outdoor cemented tanks (20 m(2)) with a stocking density of 30 fish (average weight: 20.5 g) per tank. L. rohita fingerlings were divided into five groups and fed a diet with no GP supplementation (control diet; C) or a diet supplemented with 5 g (GP5), 10 g (GP10), 15 g (GP15), or 20 g (GP20) of GP per kg of the control diet. The results showed that fish well-being, determined by measuring the condition factor, remained higher than 1.0 for all the experimental groups. The condition factors of all the groups were not significantly different between the groups, suggesting GP had no negative impact on overall fish health. Immune responses significantly improved in the groups fed with diets supplemented with GP at doses of 10 to 15 g per kg of their diet, as seen in respiratory burst activity, total immunoglobulins, and lysozyme activity at 60 and 120 days. Blood metabolic variables, particularly the albumin level, tended to show some level of improvement in the GP15-fed group. However, the effect was not significant. Total protein and globulin levels and the albumin/globulin ratio were not significantly affected by dietary GP. Importantly, fish fed the GP15 diet showed the highest resistance to the A. hydrophila challenge. In conclusion, ginger powder holds promise as a health-promoting nutraceutical for farmed L. rohita, contributing to their sustainable farming.