Chlorella pyrenoidosa improves meat quality and flavor precursors of fattening lambs by regulating jejunal microbiota and muscle metabolism via the gut-muscle axis.

This study elucidates the mechanism by which Chlorella pyrenoidosa enhances meat quality in finishing lambs via modulation of the jejunal microbiota and muscle metabolism. In a 60-day trial, 32 lambs were fed diets supplemented with 0%, 1%, 3%, or 5% C. pyrenoidosa. C. pyrenoidosa supplementation significantly improved meat color, elevated amino acid (AA) and polyunsaturated fatty acid (PUFA) levels, and reduced saturated fatty acid content in the Longissimus dorsi muscle. 16S rRNA gene sequencing identified an enrichment of specific jejunal microbes, including Bifidobacterium and Mogibacterium. Integrated microbiota-metabolome analysis indicated that C. pyrenoidosa modulated the D-amino acid metabolism pathway. Transcriptome analysis revealed the upregulation of key genes involved in fatty acid β-oxidation (carnitine palmitoyltransferase 1B, CPT1B) and amino acid synthesis (glutamic-oxaloacetic transaminase 1, GOT1). In conclusion, C. pyrenoidosa enhances lamb meat quality by remodeling the jejunal microbiota and concurrently promoting both fatty acid β-oxidation and AA synthesis in muscle.