Oral administration of Zingiber officinale and Aegle marmelos extracts enhances growth and immune functions of the shrimp Penaeus monodon against the white spot syndrome virus (WSSV)

This study was conducted to determine the effect of oral administration of Zingiber officinale and Aegle marmelos extracts on the growth performance and immunomodulatory activities of the shrimp Penaeus monodon against white spot syndrome virus (WSSV). A methanol extract of the Z. officinale rhizome and A. marmelos leaf was sprayed into a pellet feed at concentrations of 0% (control), 0.05% (treatment 1), and 0.1% (treatment 2), respectively. Shrimps fed the extract (T1) showed substantial improvements in growth performance and feed utilization efficiency when compared to the control group. Extract-fed shrimp also exhibited an increase in immune-related gene expression in comparison to controls. After 4 weeks of feeding, shrimp were injected with the white spot syndrome virus and observed for another 2 weeks to determine mortality. Compared to shrimp fed the control diet, Z. officinale and A. marmelos extract–fed shrimp displayed a decrease in hemolymph clotting time and an increase in immunological parameters such as total hemocyte count, prophenoloxidase activity, and superoxide dismutase activity both before and after viral challenge. Fourteen days after the WSSV challenge, the cumulative mortality of extract-fed shrimp was considerably lower compared to the mortality of the control group which died shortly after the challenge. Therefore, the Z. officinale and A. marmelos extracts could be used as immunostimulants to enhance the growth and resistance of shrimp against the white spot syndrome virus.