Amid fodder shortages and environmental concerns in Morocco, this study explores a transformative livestock feed strategy. By combining olive pulp (OP) and wheat straw (WS) treated with Phanerochaete chrysosporium and Fusarium oxysporum, we enhance digestibility and sustainability. Five mixing ratios were examined: 100% OP (OP), 75% OP and 25% WS (MOP), 50% OP and 50% WS (OPWS), 25% OP and 75% WS (MWS), and 100% WS (WS). Fungal treatment and ratios influence cellulose-lignin dynamics. MOP increased cellulose (13.1), OP showed an initial decrease (-8.51, -5.88 for P. chrysosporium, F. oxysporum), with cellulose rising from 4 to 8 weeks, then declining. Lignin degradation differed (P < 0.001), P. chrysosporium was efficient (24.22%±13.75 to 31.57%±20.65), MWS remarkable, and OPWS stable. Mixed substrates showed higher IVTD_imp (58.56% ± 16%, 54.18% ± 20%, 36.83% ± 18%), OP and WS lower (26.25% ± 11%, 14.43% ± 7.48%). Enhanced IVTD (4-12 weeks) seen, OPWS and MOP excelling, WS lower. In conclusion, this study unveils the potential of fungal-treated feed optimization through substrate composition and tailored treatment durations. By leveraging synergistic effects and optimizing treatment timelines, we enhance livestock feed sustainability while addressing waste management concerns. This comprehensive approach holds promise for achieving both nutritional and environmental goals in livestock production.