Effect of long-term dietary ginger (Zingiber officinale Roscoe) on white blood cells, red blood cells and disease resistance against Streptococcus agalactiae in Nile tilapia (Oreochromis niloticus)

Abstract

The study was performed to examine the effect of long-term dietary ginger (Zingiber officinale
Roscoe) on white blood cells (WBC), red blood cells (RBC) and disease resistance against Streptococcus
agalactiae in Nile tilapia (Oreochromis niloticus). The Nile tilapia (0.36 + 0.05 g initial body weight)
were fed with diets supplemented with ginger at 0 (control), 1, 3, 5 and 7 g/kg of feed for 40 days. After,
fish were challenged with S. agalactiae. Survival rate and the number of WBC and RBC were recorded.
Fish fed diets supplemented with ginger in all levels showed survival rate after challenged higher than
control. Significantly increased survival rate were found in fish fed with ginger at 5 g/kg of feed (p<0.05).
The number of WBC and RBC after challenged was significantly increased in fish fed with ginger at 5
and 7 g/kg of feed compared to the control (p<0.05). In conclusion, the use of dietary ginger as an

immunostimulant for 40 days, diet supplemented with ginger at 5 g/kg of feed was suitable level to improve
the number of WBC and reduce susceptibility to S. agalactiae in Nile tilapia.