# Effects of Immunostimulants on Physiological Performances, Immune Gene Expression, Liver, and Intestinal Protection Against Vibrio parahaemolyticus Infection in Juvenile Asian Seabass (Lates calcarifer)

## TL;DR

This study explores how adding immunostimulants like ginger, garlic, and palm carotene to the diet of juvenile Asian seabass improves their immune response and protects against bacterial infection.

## Contribution

The study introduces a combination of natural immunostimulants as a potential immune booster in aquaculture feed for Lates calcarifer.

## Key findings

- Palm carotene supplementation reduced intestinal inflammation and liver damage in infected fish.
- Combined treatment with ginger, garlic, and palm carotene improved intestinal and liver protection compared to individual supplements.
- The combination increased goblet cell numbers and intestinal villus surface area in infected fish.

## Abstract

The present study aims to develop a more valuable innovative aquaculture feed for the sustainable Lates calcarifer aquaculture industry. An experiment with a completely random design was developed with five groups containing 0% immunostimulant and 0.5% ginger, 1.0% garlic, 0.15% palm carotene alone or in combination. Each diet was randomly assigned to triplicate groups of 30 fish (10.06 ± 0.09 g) per tank. The fish were fed once daily to apparent satiation. Throughout the 56-day feeding trial, the results suggest that although no significant differences were observed among almost all experimental groups in growth performance, feed efficiency, fish composition and disease resistance, the palm carotene supplementations downregulated intestinal tumor necrosis factor alpha (TNF-α) and interleukin (IL)-6 expression, decreased sum scores of liver pathological changes, increased intestinal villus surface (VS) compared with the control group. Moreover, the combined treatment shows more promising immune gene expression (intestinal IL-1 beta (IL-1β) was also downregulated compared to the control), liver and intestinal protection (lower sum scores of liver pathological changes and larger intestinal VS than palm carotene alone supplementation, goblet cell (GC) number per intestinal villus was also increased compared to the control) effects on L. calcarifer infected with Vibrio parahaemolyticus. Therefore, a combination of 0.5% ginger, 1.0% garlic, and 0.15% palm carotene in the diet of L. calcarifer can be used as an immune booster due to fishmeal substitution to obtain better immunocompetence.