Extrusion Puffing Combined with Irpex lacteus Fermentation Strategy for Peach Branch Feed Valorization

Valorizing peach pruning residues into alternative feed is a potentially sustainable strategy. In this study, we evaluated the effects of extrusion puffing (EX) and white-rot fungi (Phanerochaete chrysosporium, Irpex lacteus, and Phlebia acerina) on the lignocellulose composition of peach branches. We selected I. lacteus as the best-performing fungus for subsequent investigations of its effects on enzyme activities, in vitro rumen fermentation, and metabolomic analyses. Compared with the control, EX alone reduced the concentrations of cellulose, hemicellulose, and lignin by 27.3%, 22.4%, and 9.0%, respectively. The EX combined with I. lacteus (EI) treatment showed high selectivity for lignin degradation relative to cellulose degradation and increased β-glucosidase activity in the middle stage (days 14 and 21) compared with I. lacteus treatment (p < 0.05). Through metabolomic analysis, we identified organic acids and their derivatives (mainly carboxylic acids) as the most abundant superclass. On day 28, betaine and L-leucine were enriched in the fermented samples, and their abundances appeared to be descriptively associated with the enzyme activity patterns observed at this time point. In conclusion, the EI treatment represents a potential approach for altering the composition of peach branches; however, its practical benefits must be weighed against the energy input required and the complexity of the process. In this work, we provide a theoretical foundation for feed-oriented valorization of orchard pruning residues. Further studies are needed to assess economic feasibility and scale-up performance.