Abstract

This study compared the effects of structurally distinct starches on growth performance, intestinal microbiota, and liver health in largemouth bass to provide scientific evidence for starch utilization in aquafeeds. Three isonitrogenous and isolipidic diets (47.78% crude protein, 10.76% crude fat) containing distinct starch sources were formulated: common corn starch (CS), waxy corn starch (WCS), and high-amylose corn starch (HACS). Each diet was fed to triplicate groups of 20 fish (initial average weight: 8.49   g) in a recirculating aquaculture system for 65 days. The results showed that the HACS group exhibited the highest final body weight (FBW), weight gain rate (WGR), and specific growth rate (SGR), followed by the CS and WCS groups ( P < 0.05). Furthermore, compared with the WCS group, the HACS group showed a significant increase in the concentrations of propionate and butyrate in the intestinal digesta ( P < 0.05). Additionally, hepatic transcriptome analysis revealed that the differently expressed genes (DEGs) in the HACS and WCS groups were predominantly enriched in Gene Ontology (GO) terms and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways related to fatty acid metabolism and inflammatory regulation. Moreover, compared with the WCS group, the HACS group significantly reduced serum total cholesterol (TC) and triglyceride (TG) levels, along with fewer hepatic lipid droplets ( P < 0.05). This was accompanied by downregulated the mRNA expression of hepatic lipid synthesis genes including sterol regulatory element binding transcription factor 1 (srebf1), acetyl-CoA carboxylase 1 (acc1), fatty acid synthase (fasn), stearoyl-CoA desaturase (scd) ( P < 0.05), while upregulated the mRNA expression of lipid catabolism genes such as peroxisome proliferator-activated receptor α (pparα), carnitine palmitoyltransferase 1 (cpt1), acetyl-CoA acyltransferase 2 (acaa2), adipose triglyceride lipase (atgl), hormone-sensitive lipase (hsl) and corresponding prote