Dietary Hypsizygus marmoreus Stipe May Improve Survival of Juvenile Largemouth Bass (Micropterus salmoides) Through Metabolic Regulation.

The stipe of Hypsizygus marmoreus is a low-value byproduct generated during mushroom processing. Reutilization of this agricultural waste as a functional feed additive may provide both economic and environmental benefits for sustainable aquaculture. This study evaluated the effects of dietary H. marmoreus stipe (HMS) supplementation on the growth performance and survival of juvenile Micropterus salmoides and explored the underlying metabolic and transcriptional responses. Juvenile largemouth bass (initial body weight: 1.13 ± 0.05 g) were fed diets containing 0% (HMS0), 5% (HMS5), or 10% (HMS10) HMS for 46 days. HMS supplementation did not significantly affect growth performance but significantly increased survival rate in both HMS5 and HMS10 groups. Widely targeted metabolomic profiling suggested that dietary HMS may drive prominent shifts in the hepatic and gastric metabolic profiles, with potential changes observed in pathways associated with pyrimidine metabolism, glycerophospholipid metabolism, and ABC transporters. Hepatic transcriptomic analysis further identified differentially expressed genes enriched in these pathways. Integrated multi-omics analysis indicated potential coordinated associations between key metabolites, including orotic acid, ureidosuccinic acid, LPG (16:1), and Val-Cys, and genes involved in nucleotide metabolism, lipid metabolism, and transporter functions, such as DPYD (dihydropyrimidine dehydrogenase), NDK (nucleoside diphosphate kinase), ENTP5 (ectonucleoside triphosphate diphosphohydrolase 5), NT5D2 (5'-nucleotidase domain containing 2), GPT3L (glycerol-3-phosphate acyltransferase-like), ABCA1 (ATP-binding cassette subfamily A member 1), and ABCD4 (ATP-binding cassette subfamily D member 4). In addition, antioxidant enzyme activities were significantly enhanced in the HMS5 group, whereas no further improvement was observed at the 10% supplementation level. Collectively, these findings suggest that dietary HMS supplementation may enhance the survival of largemouth bass via coordinated metabolic regulation and antioxidant responses. This study highlights the potential application of mushroom-processing byproducts as sustainable functional feed ingredients in aquaculture.