AimIn this study, the biological variation for improvement of the nutritive value of wheat straw by 12 Ceriporiopsis subvermispora, 10 Pleurotus eryngii and 10 Lentinula edodes strains was assessed. Screening of the best performing strains within each species was made based on the invitro degradability of fungal-treated wheat straw. Methods and ResultsWheat straw was inoculated with each strain for 7weeks of solid state fermentation. Weekly samples were evaluated for invitro gas production (IVGP) in buffered rumen fluid for 72h. Out of the 32 fungal strains studied, 17 strains showed a significantly higher (P<005) IVGP compared to the control after 7weeks (2277ml g(-1) OM). The three best Ceriporiopsis subvermispora strains showed a mean IVGP of 2970mlg(-1) OM, while the three best P. eryngii and L. edodes strains showed a mean IVGP of 2578 and 2915mlg(-1) OM, respectively. ConclusionCeriporiopsis subvermispora strains show an overall high potential to improve the ruminal degradability of wheat straw, followed by L. edodes and P. eryngii strains. Significance and Impact of the StudyLarge variation exists within and among different fungal species in the valorization of wheat straw, which offers opportunities to improve the fungal genotype by breeding.