# Impacts of dietary sodium alginate as a prebiotic on the oriental river prawn (Macrobrachium nipponense): A comprehensive analysis of growth, physiology, immunity, antioxidant, and metabolism

## TL;DR

Adding sodium alginate to the diet of oriental river prawns improves growth, digestion, immunity, and gut health.

## Contribution

This study demonstrates that dietary sodium alginate enhances growth and physiological health in Macrobrachium nipponense through multiple biological mechanisms.

## Key findings

- Sodium alginate at 4.0 g/kg significantly improved growth and feed efficiency in M. nipponense.
- Supplementation increased digestive enzyme activity and promoted beneficial gut microbiota.
- Gene expression related to growth, immunity, and metabolism was upregulated with sodium alginate.

## Abstract

•Sodium alginate improved growth and feed efficiency in M. nipponense.•Digestive enzyme activity significantly increased under sodium alginate-supplemented diets.•Antioxidant defenses enhanced via reduced MDA and elevated T-AOC levels.•Gut microflora shifted toward beneficial LAB in response to sodium alginate supplementation.•Gene expression of markers related to growth, immunity, and metabolism was upregulated by sodium alginate.

Sodium alginate improved growth and feed efficiency in M. nipponense.

Digestive enzyme activity significantly increased under sodium alginate-supplemented diets.

Antioxidant defenses enhanced via reduced MDA and elevated T-AOC levels.

Gut microflora shifted toward beneficial LAB in response to sodium alginate supplementation.

Gene expression of markers related to growth, immunity, and metabolism was upregulated by sodium alginate.

The effects of dietary sodium alginate supplementation on Macrobrachium nipponense were evaluated over a 60-day feeding trial, with emphasis on growth, hematological, immune-physiological responses, and metabolic characteristics. Juvenile prawns with an initial average weight of 1.47 ± 0.05 g were assigned to diets containing 0.0 (control), 0.5, 1.0, 2.0, or 4.0 g/kg sodium alginate. Among all the examined water quality indicators, dissolved oxygen (DO) was the only parameter that showed a statistically significant rise with increasing levels of sodium alginate supplementation, with the 4.0 g/kg group showing the maximum value of DO concentration (P < 0.05). Furthermore, growth metrics and survival rates (SR) were significantly enhanced in prawns receiving 2.0 and 4.0 g/kg sodium alginate compared to other treatments (P < 0.05). Hemato-biochemical indices generally decreased following sodium alginate supplementation, whereas levels of high-density lipoprotein (HDL) and low-density lipoprotein (LDL) were elevated (P < 0.05). Most immune parameters and antioxidant enzyme activities demonstrated positive modulation in response to the dietary intervention (P < 0.05), although glutathione peroxidase (GPx), acid phosphatase (ACP), and alkaline phosphatase (AKP) activities did not differ significantly among groups (P > 0.05). Diets supplemented with 4.0 g/kg sodium alginate notably enhanced digestive enzyme activities, promoted beneficial intestinal microbiota, and improved body composition (P < 0.05). Additionally, sodium alginate intake influenced the expression of genes associated with growth, immune function, and metabolism (P < 0.05). Overall, these findings support the dietary inclusion of 4.0 g/kg sodium alginate to optimize growth, physiological condition, and metabolic health in M. nipponense.

Image, graphical abstract