Mechanistic Impacts of Black Soldier Fly Substitution for Soybean Protein on the Rumen Microbiome Host Metabolic Axis in Qianbei Goats

This study aimed to elucidate how heat-treated full-fat black soldier fly larvae (BSF), used as a substitute for soybean meal, modulates rumen microbiome function and host systemic metabolism in ruminants. Thirty Qianbei Ma goats were randomly assigned to three dietary treatments: a control diet (CON), a diet containing untreated BSF (UBSF), or a diet containing heat-treated BSF (HTBSF). An integrated multi-omics framework combining rumen fermentation measurements, metagenomics, serum metabolomics, and immune and antioxidant indicators was applied to characterize responses along the rumen microbiome-host metabolism axis. Compared with CON, HTBSF significantly increased average daily gain and shifted rumen fermentation profiles. Metagenomic analyses showed that BSF supplementation increased rumen microbial alpha diversity and enriched functional genes involved in nitrogen metabolism, amino acid biosynthesis, and carbohydrate degradation. Serum metabolomics indicated that HTBSF altered systemic lipid metabolism, redox balance, and immune-inflammatory pathways, consistent with changes in key metabolites including sphingolipids, bile acids, and polyamines. Collectively, these findings suggest that BSF improves growth performance by restructuring the rumen microbial community and its functional network, thereby promoting coordinated reprogramming of host metabolism.