A study led by a research team at the Institute of Hydrobiology (IHB) of the Chinese Academy of Sciences revealed the potential of seabuckthorn and gallic acid in enhancing fish mucosal immunity and improving disease resistance, and explored the effects of these plant-derived additives in combating foodborne enteritis and improving overall health in farmed fish. This study was published in Aquaculture.

Aquaculture plays a crucial role in providing a sustainable protein source. However, the high cost and limited supply of fishmeal have led to the increased use of plant proteins such as soybean meal (SBM) in aquafeeds. Plant-based proteins are cost-effective, and can cause side effects such as foodborne enteritis and liver issues, particularly in carnivorous fish species. This leads to higher susceptibility to infectious diseases, damaging the health and reducing survival rates of farmed fish.

In response to these challenges, the IHB team led by Prof. XIA Xiaoqin and Assoc. Prof. WU Nan conducted a study to investigate the effects of seabuckthorn and its core component, gallic acid, in preventing and treating soybean meal-induced enteritis (SBMIE) in grass carp. This study builds upon previous studies in zebrafish where seabuckthorn and gallic acid were shown to play significant protective roles in the gut-liver axis and mucosal immunity.

Researchers conducted feeding experiments to measure the immunity and metabolism of the gut-liver axis. The results indicated that both seabuckthorn and gallic acid significantly enhanced the intestinal and liver immunity of grass carp, supporting mucosal health and preventing foodborne enteritis. These additives also improved the antimicrobial capacity of mucous membranes, which greatly increased survival rates in farmed fish.

When comparing seabuckthorn with gallic acid, researchers found that seabuckthorn performed better in promoting lipid metabolism, controlling Aeromonas hydrophila infections, reducing inflammation, and increasing probiotic abundance; in contrast, gallic acid provided notable benefits in protecting the mucosal barrier and improving respiratory efficiency by increasing the gill filament space.

Furthermore, researchers compared the protective effects of seabuckthorn with gallic acid against Aeromonas hydrophila, a common fish pathogen. They found that both seabuckthorn and gallic acid significantly enhanced intestinal and liver immunity, supported mucosal health, and improved disease resistance. Their inclusion in fish feed led to higher survival rates, enhanced antimicrobial resistance, and better mucous membrane integrity.

The optimal concentrations for both additives were determined in this study with seabuckthorn being 9.5 g/kg and gallic acid being 1.2 g/kg. Grass carp fed SBM-based diets with these additives showed improved immunity, mucosal health, and resistance to foodborne enteritis. In addition, the analysis of 16S rRNA gene sequencing revealed a reduction in pathogenic bacteria and an increase in beneficial microbiota, further supporting the gut-liver axis.

This study underscores the potential of plant-derived additives as a sustainable and healthier alternative to fishmeal, and offes a more resilient and eco-friendly approach to fish farming.