Effect of white-rot basidiomycetes-treated wheat straw on rumen fermentation in artificial rumen

This study evaluated three white-rot basidiomycetes for their potential to improve the ruminal degradation of wheat straw. Pleurotus ostreatus (PO), Pleurotus ostreatus-mutant (PO-M) and Trametes gibbosa (TG) were incubated on wheat straw for 30 days at 28 degrees C. Neutral detergent fiber (NDF), acid detergent fiber (ADF), crude protein and in vitro dry matter digestibility (IVDMD) were determined. The results demonstrated increasing crude protein and ash contents (%) in the fungi-treated straws. The IVDMD values were also increased. Compared to untreated wheat straw (UWS), the NDF and ADF contents were reduced in fungi-treated straw (TWS). Out of the three fractions - hemicellulose, cellulose and lignin-hemicellulose showed the largest proportionate loss and lignin the smallest in all three fungi-treated straws. TWS with Pleurotus ostreatus (TWS-PO), Pleurotus ostreatus-mutant (TWS-PO-M) and Trametes gibbosa (TWS-TG) together with barley (80:20%) were used as the experimental diets in the artificial rumen. UWS with barley (80:20%) served as the control diet. The results revealed significantly higher IVDMD values, NDF, ADF and cellulose digestibilities (%) with the experimental diets. The production of propionic acid decreased, n-butyric, n-valeric and iso-valeric acids (mmol/day(-1)) increased and the volatile fatty acid (VFA) production expressed in mol VFAs.kg(-1) digested dry matter decreased in experimental diets. The total microbial production also decreased at fermentation in the experimental diets.