Sugarcane bagasse, a complex substrate, when differentiated into four fractions of particle sizes (<1 mm, 1-3 mm, 3-5 mm, 5-10 mm) with a view to enhancing its nutritive value as animal feed rather than production of fungal protein for human consumption, showed a varying pattern of degradation by white-rot fungi and varying in vitro rumen digestions. The fractions of bagasse were assessed for their bioconversion efficiencies in terms of disappearance of lignin and change in digestibility using Pleurotus sp. P7, Agrocybe aegarita A1, Pleurotus eryngii Pleurotus sp. P1 and Kuehneromyces mutabilis. The P. eryngii improved the digestibility of all the bagasse fractions. The mechanical separation of a substrate can be of significance when it is utilized as a material to be fermented by white-rot fungi to produce enriched animal feed.