Dietary magnesium hydride supplementation positively influences growth performance, intestinal histology, intestinal microbiota, and metabolites in juvenile largemouth bass (Micropterus salmoides)

In present study, the survival, growth performance, intestinal histology, intestinal microbiota, and metabolites of largemouth bass ( Micropterus salmoides ) fed with diets supplemented with different concentrations of magnesium hydride (MgH 2 ), containing 0 mg/kg (H0), 10 mg/kg (H10), 20 mg/kg (H20), and 30 mg/kg (H30) hydrogen molecules. Four hundred and eighty juvenile largemouth bass (38.24 ± 2.37) g were cultured for 8 weeks, and the results showed that dietary supplementation with MgH 2 improved fish survival rate (SR), weight gain rate (WGR), and length, while relative fatness was reduced. The best growth effect was observed in the H20 group. The MgH 2 supplementation group also presented significantly increased villus length, basal layer thickness, and goblet cell number. The intestinal microbiota of the MgH 2 supplementation group was significantly different compared to the control group. The relative abundance of Fusobacteriota and Proteobacteria significantly increased in MgH 2 supplementation group, while the abundance of Firmicutes was decreased. Among them, higher relative abundance of anaerobic bacteria such as Romboutsia , Clostridium_Sensu_Stricto_1 , norank_f_ Barnesiellaceae , and Unclassified_o_ Bacteroidales were observed in the MgH 2 supplementation group. In addition, significant changes in the levels of several intestinal metabolites including N(6)-Methyllysine, irinotecan, capsidiol, taurochenodeoxycholate-7-sulfate, prostaglandin F1a, and caffeic acid 3-glucoside was observed in MgH 2 supplementation group. And changes in intestinal microbiota were significantly correlated with changes in metabolite levels. Overall, dietary supplementation with MgH 2 (20 mg/kg hydrogen molecules) exhibits positive effects on M. salmoides farming based on growth performance, intestinal histology, intestinal microbiota, and metabolites explored in the present study. • Dietary MgH 2 supplementation improve survival and growth of Fish. • Dietary MgH 2 supplementation enhanced intestinal health. • Dietary MgH 2 supplementation modulate intestinal microbiota composition. • Dietary MgH 2 supplementation change intestinal metabolite levels. • Correlation between intestinal microbiota and metabolites.