Duck-egg white hydrolysate supplementation enhances muscle endurance and fatigue resistance during high-intensity exercise

Recent processing advances, including separating and marinating duck yolks, provide alternatives to traditional salted duck eggs. However, separated duck-egg white remains a nutritious agricultural byproduct due to its unpleasant odor and low consumer acceptance. Duck-egg white hydrolysates (DEWHs), produced by protease-A hydrolysis, are rich in branched-chain amino acids (BCAAs) and imidazole dipeptides like carnosine and anserine. In mice undergoing high-intensity exercise, DEWH supplementation increased hindlimb muscle mass, soleus-muscle-fiber size, and performance in swimming and treadmill tests. DEWHs improved lactate clearance, stabilized post-exercise blood glucose, and elevated muscle and liver glycogen (p < 0.05). DEWHs also improved exercise-induced muscle injury markers (AST, BUN, and CK) and inflammatory cytokines (IL-1β, IL-6, and TNF-α), and decreased antioxidant capacities (reduced GSH, SOD, and GSH-Px) (p < 0.05). In C2C12 myotubes, DEWHs counteracted dexamethasone (Dex)-induced mitochondrial dysfunction, suppressed protein synthesis, and ATP depletion while decreased protein synthesis signaling (p-p70S6K/p70S6K and p-4EBP1/4EBP1), and upregulated protein degradation markers (p-FoxO1/FoxO1 and TRIM63) and mitochondrial biogenesis factors (NRF1 and PGC-1α) were also mitigated (p < 0.05). Additionally, DEWHs enhanced citrate synthase and cytochrome c oxidase activities, boosting ATP production (p < 0.05). These findings suggest DEWHs enhance muscular endurance, reduce fatigue, and mitigate oxidative and inflammatory responses by modulating protein turnover and energy production, offering a novel protein supplement and value-added use for duck-egg white byproduct surplus.