Efficacy of aromatic plants Zingiber officinale and Syzygium aromaticum extracts as natural immunostimulants on survival, growth performance, and immune response of farmed prawn Penaeus monodon juveniles

Abstract

Herbal plants contain active bio-compounds that may stimulate the nonspecific immune system of animals and, as a result, play an important role as growth promoters and immunostimulants. To this end, the present study was set up to assess the efficacy of herbal extracts derived from two aromatic plants, ginger (Zingiber officinale) and clove (Syzygium aromaticum), as natural immunostimulants on the survival, growth performance, and immune response of farmed prawn Penaeus monodon juveniles. Seven experimental diets with an average of 40% CP were supplemented with herbal extracts at percentages of 0, 1, 2, and 3, then administered to prawns with an average size of 0.16 ± 0.12 g (at stocking) for 14 weeks, followed by a 2-week challenge test against Vibrio harveyi. Extract inclusion positively impacted weight gain, feed conversion ratio (FCR), and specific growth rate (SGR). Also, extract inclusion significantly improved the survival rate of the prawn after the challenge (p < 0.05). Significantly high total hemocyte counts (THC) were observed in the 2% Z. officinale and 3% S. aromaticum treated groups before the challenge. The study indicates that the groups exposed to the herbal extracts derived from ginger (Z. officinale) and clove (S. aromaticum) demonstrated significant resistance against bacterial infection (p < 0.05). Ginger and clove extracts have been observed to optimally boost P. monodon growth, survival, and immunity, at inclusion levels of 2 and 3%, respectively, hence hold promising potential as natural alternatives to antibiotics in managing Vibrio harveyi infections and promoting the growth, survival, and immunity of P. monodon in prawn farming systems.