Changes in Dry Matter Digestibility and Composition of Bioconverted Mustard Biomass by two <i>Pleurotus </i>spp. Under Mushroom Growing Conditions

Abstract

Two species of white rot fungi, <i>Pleurotus florida </i>and <i>P. citrinopileatus </i>were grown on haulms of brassica plant for fruit body production as well as for studying suitability of the spent substrate as ruminant feed. The degrading capacity of these two species &nbsp;as well as production efficiency of fruit bodies and possible use of the resulting highly digestible protein enriched spent substrate as ruminant feed following fungal fermentation, were investigated. Biological efficiency was found to be higher in biomass inoculated with <i>P. florida </i>(96.6 per cent) than that with <i>P. citrinopileatus </i>(85.1 percent ). Loss of organic matter was, however, highest in sets inoculated with <i>P. citrinopileatus </i>than that with <i>P. florida </i>after all three degradation periods showing maximum after third flush. Bioconverted spent substrate after first flush was superior in chemical composition as well as digestibility as ruminant feed when compared to that after spawning period and third flush. After all three periods, preferential degradation of hemicellulose (maximum 40.1 ± 0.5 per cent d w by <i>P. citrinopileatus) </i>over cellulose and lignin were observed, and delignification was highest by <i>florida</i><i> </i>(33.1 ± 0.2 per cent d w) than by <i>P. citrinopileatus </i>(27.9 ± 0.6 percent d w) after third flush. Crude protein of the bioconverted substrate increased up to the spawning period (higher value of 7.8 ± 0.4 per cent d w by <i>P.florida)</i>, but decreased thereafter. Protein enriched spent substrate following the ‘low cost production’ of the edible mushrooms, parti cularly after first flush, resulted improvement of dry matter digestibility, more so by <i>P. florida </i>(+25.3 per cent for IVCD, +28.9 per cent for IVRD) than by <i>P. citrinopileatus </i>(+23.1 per cent for IVCD, +25.8 per cent for IVRD). Results of this study proved <i>P.</i> <i>florida</i><i> </i>to be more biologically efficient and effective delignifier organism for the production of highly digestible mycoproteinrich fermented ruminant feed than <i>P.citrinopileatus.</i>