Effect of Dietary Addition of Lentinus edodes on Rumen Flora, Lactation, and Health of Dairy Goats

<i>Lentinus edodes</i> (LE) is a nutrient-rich medicinal fungus with potential applications in animal nutrition; however, its effects on dairy goats remain underexplored. This study investigated the impact of dietary LE addition on rumen microbiota, metabolic profiles, serum immunity, and milk quality in lactating dairy goats. Twenty Saanen goats were randomly assigned to a control group (CON, basal diet) or an LE group (basal diet + 25 g <i>Lentinus edodes</i>) for 56 days. Rumen fluid, serum, and milk samples were analyzed using 16S rDNA sequencing, metabolomics, and biochemical assays. The results showed that the addition of LE altered the microbial composition, decreasing the abundance of fibrobacterial flora and <i>Treponema</i> (<i>p</i> < 0.05) while increasing VadinHA49. Metabolomic analysis revealed elevated fumaric acid, lysophospholipids (LysoPE, LysoPG), and D-quinic acid in the rumen (<i>p</i> < 0.05). Serum immunoglobulin A (IgA), immunoglobulin G (IgG), total antioxidant capacity (T-AOC), superoxide dismutase (SOD), catalase (CAT), and tumor necrosis factor-α (TNF-α) levels were significantly enhanced (<i>p</i> < 0.05). The milk somatic cell count (SCC) was reduced by 52.8% (<i>p</i> = 0.005) at day 56, and protein, fat, and total solids increased significantly (<i>p</i> < 0.05). Enrichment of functional metabolites such as D-arabitol and D-tryptophan in milk further highlighted LE's role in improving product value. These findings demonstrate that LE optimizes rumen flora, enhances antioxidant and immune functions, and improves milk quality, supporting its use as a functional feed additive for dairy goats.