Determination of the Modulatory Effects of Selenium-Enriched Egg Powder on the Physiological Immune Response and Cecal Microbiota of Kunming Mice

Se-enriched functional eggs are prevalent nowadays, which may help improve body health and anti-oxidant capacities. However, the modulatory effects on cecal microbiota are still limited. This study aims to investigate the underlying mechanism of Se-enriched egg powder in modulating the cecal microbiota of Kunming mice. A total of 72 mice were randomly assigned to a control treatment (CON), a conventional egg powder treatment (EP), and four gradient Se-enriched egg powder treatments (EPS1–EPS4, with the Se content ranging from 0.01 to 0.04% of total dietary content) for a 35-day feeding procedure. Parameters included growth performance, tissue Se content distribution, serum anti-oxidant capacities (GSH-Px, SOD, MDA), and immune cytokines (IgG, TNF-α), and cecal microbiota composition was further measured. Results showed dietary 0.02% (EPS2) significantly improved growth performance, physiological anti-oxidant defenses, and cytokine TNF-α (p < 0.05), while significantly reducing feed conversion ratio and malondialdehyde (MDA) compared with CON (p < 0.05). Metagenomic results revealed that Se-enriched egg powder significantly increased bacterial α-diversity and the abundance of Akkermansia, Bacteroides, and Bifidobacterium (p < 0.05), while significantly decreasing Desulfovibrio and Escherichia-Shigella (p < 0.05). In conclusion, dietary supplementation with Se-enriched egg powder effectively enhances growth performance, anti-oxidant capacity, and immunity, mainly through the promotion of beneficial bacteria diversity and suppression of pathogens.