Dietary Broussonetia papyrifera flavonoids affect broiler muscle fiber development, meat quality, antioxidant capacity, and muscle metabolomic profiles.

BACKGROUND: Intensive and antibiotic-free broiler production requires nutritional strategies that support meat quality and redox stability. Broussonetia papyrifera flavonoids (BPF) have antioxidant and metabolic regulatory activities, but their effects on broiler muscle development and muscle metabolomic profiles remain unclear. METHODS: A total of 240 healthy 1-day-old Arbor Acres broilers were randomly assigned to four dietary treatments for 42 days: a basal diet without BPF (control) or basal diets supplemented with 100, 200, or 300 mg/kg BPF (groups I-III). Meat quality, muscle morphology, antioxidant indices, and non-targeted LC-MS/MS metabolomic profiles were evaluated in pectoral and thigh muscles. RESULTS: BPF improved selected water-holding capacity indices by reducing pectoral cooking loss and thigh drip loss (P < 0.05), with no significant effect on shear force (P > 0.05). BPF also altered pH and color traits, reduced muscle fiber diameter, increased fiber density, enhanced T-AOC, T-SOD, and GSH-Px activities, and decreased MDA content, with the most consistent responses observed at 200 mg/kg. Non-targeted metabolomics of the control and 200 mg/kg groups identified 75 differential metabolites in pectoral muscle and 65 in thigh muscle (P < 0.05). Enriched pathways were mainly associated with amino acid metabolism, phenylpropanoid biosynthesis, lipid metabolism, cholesterol metabolism, fatty acid digestion and absorption, and oxidative stress-related metabolic regulation. CONCLUSION: Dietary BPF, particularly at 200 mg/kg, improved selected broiler meat quality, muscle fiber traits, and antioxidant status. The metabolomic findings provide exploratory evidence of muscle-specific metabolic remodeling that requires targeted validation.