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

Abstract

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°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 isovaleric 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.