Effect of Four Species of White Rot Fungi on the Chemical Composition and In Vitro Rumen Degradability of Naked Oat Straw

Abstract

This study evaluated the treatment of naked oat straw with four species of white rot fungi (Phanerochaete chrysosporium, Pleurotus ostreatus, Irpex lacteus, and Phlebia acerina) for solid-state fermentation in terms of the changes in chemical composition, lignocellulosic structure, and in vitro ruminal digestion. All the fungi were inoculated in naked oat straw for 28 days to evaluate the changes of above indexes weekly. The results showed that all of the fungus species could alter the multi-scale structure of the straw to different extents when compared to the control. P. acerina caused the greatest degradation of acid detergent lignin (46.51%), followed by P. chrysosporium (44.20%), while P. ostreatus and I. lacteus were slightly weaker in terms of acid detergent lignin degradation than the other two species. The dry matter loss for all treatments was below 20% except for P. chrysosporium, and all of the fungus species caused holocellulose degradation during treatment, with P. chrysosporium in particular exhibiting non-selectivity. Compared with the other fungi, I. lacteus treatment resulted in moderate losses of hemicellulose and cellulose (31.92% and 15.44%, respectively). In addition to P. chrysosporium, the in vitro dry matter digestion was improved with treatment by the other three fungi. Treatment with I. lacteus, led to improvement in dry matter, neutral detergent fiber and acid detergent fiber degradability of 16.22%, 37.12%, and 40.05%, respectively. Irpex lacteus outperformed the other three fungi in terms of decomposing three-dimensional structures and improving the nutritional value of naked oat straw.