Effects of Atractylodes macrocephala polysaccharide on growth performance, serum biochemical indexes, and intestinal microflora of largemouth bass (Micropterus salmoides)

Introduction As the aquaculture industry intensifies to enhance production efficiency and capacity, the risk of disease outbreaks in high-density systems, such as those for largemouth bass, has escalated. This necessitates the exploration of novel strategies for disease prevention and control. Studies have shown that Atractylodes macrocephala polysaccharide (AMP) possesses the functions of promoting growth and enhancing immune capacity, making it a potential feed additive in animal production. Methods This study aimed to assess the impact of AMP on the growth performance, serum biochemical indices, and intestinal flora structure of largemouth bass. A total of 360 healthy largemouth bass (mean weight: 15.25 ± 1.29 g) were randomly assigned to four groups, each with three replicates. The groups were fed diets supplemented with 0% (Group D, control group), 0.4% (Group A), 0.8% (Group B), or 1.2% (Group C) AMP for 42 days. Results The results showed that the addition of an appropriate amount of AMP in the feed significantly improved the weight gain rate (WGR) and specific growth rate (SGR) of largemouth bass, reduced the feed conversion ratio (FCR), and enhanced growth performance. AMP reduced the levels of AST and ALT, indicating a hepatoprotective effect on largemouth bass, with significant differences from the control group (P < 0.05). AMP also improved the intestinal microbiota composition of largemouth bass, positively affecting intestinal health. The analysis of intestinal microbiota revealed 1,288 amplicon sequence variants (ASVs) in the intestine of largemouth bass in Group B, dominated by Firmicutes and Bacteroidota. In contrast, Group C (1.2%) had 920 ASVs, with Fusobacteriota and Firmicutes as the major components, while the relative abundance of Firmicutes was lower, showing significant differences from the control Group D. The functional analysis of intestinal microbiota based on KEGG showed significant differences (P < 0.05) among the four groups in Carbon metabolism, Biosynthesis of amino acids, and Metabolic pathways. Discussion The study concludes that the inclusion of AMP at 0.8% – 1.2% in the feed can enhance the growth performance and intestinal health of largemouth bass, offering a promising strategy for disease prevention and control in intensive aquaculture settings.