# Effects of Dietary Chitosan on Growth, Antioxidant Capacity, Non-Specific Immunity, and Intestinal Health of the Mud Crab, Scylla paramamosain

## TL;DR

Adding chitosan to mud crab diets improves their growth, immunity, and gut health, making it a promising supplement for aquaculture.

## Contribution

This study demonstrates chitosan's effectiveness as a functional feed additive for mud crabs, offering practical dosage insights.

## Key findings

- Chitosan at 2 g/kg significantly improved growth metrics like final body weight and specific growth rate.
- Chitosan reduced oxidative stress and enhanced antioxidant enzyme activity in mud crabs.
- Chitosan modulated gut microbiota, increasing beneficial bacteria and improving intestinal health.

## Abstract

As the mud crab aquaculture industry grows, improving its health and growth performance has become a critical focus. Chitosan, a bioactive polysaccharide, holds the potential to modulate the physiological functions of aquatic organisms. This study explored the impact of supplementing the diet of mud crabs with different concentrations of chitosan. The results showed that appropriate supplementation levels simultaneously enhanced growth performance, improved antioxidant capacity and immunity, and modulated gut microbiota structure. Overall, the findings confirm the potential of chitosan as a functional feed additive in mud crab farming, providing a dosage reference and theoretical support for its practical application.

This study investigated the effects of dietary chitosan supplementation at levels of 0, 0.5, 1, 2, 4, and 8 g/kg on the mud crab (Scylla paramamosain) during an eight-week feeding trial. Results revealed significant improvements in final body weight (FBW), weight gain rate (WGR), and specific growth rate (SGR) as chitosan levels increased, with the 2 g/kg group showing the strongest effects (p < 0.05). Chitosan supplementation also elevated crude protein content in the whole body, muscle, and hepatopancreas (p < 0.05). Moreover, it notably reduced malondialdehyde (MDA) levels in hemolymph and hepatopancreas while enhancing antioxidant enzyme activity (p < 0.05). Chitosan at doses of 1–4 g/kg also significantly increased the activity of non-specific immune enzymes in hemolymph (p < 0.05). Additionally, chitosan enhanced mRNA expression of immune-related genes in the hepatopancreas (p < 0.05). According to gut microbiota study, 2 g/kg chitosan raised the relative abundance of advantageous gut bacteria and modulated microbial composition. In conclusion, appropriate dietary chitosan supplementation successfully stimulates mud crab growth, strengthens immunological and antioxidant systems, and improves intestinal health.