Effect of fungus-treated straw on ruminal fermentation in vitro

Abstract

The effects of different substrates (hay, untreated wheat straw (UWS), wheat straw treated with Polyporus ciliatus (TWS-PC) or Lentinus tigrinus (TWS-PX)) on rumen microbial activity were studied using a semi-continuous fermenter and the rumen simulation technique (Rusitec). The substrates were fermented together with barley (80:20) and each diet contained 13% crude protein after the addition of urea in McDougall's buffer. After 48 h of incubation, the most intensive fermentation occurred with the hay diet. The treatment of straw with fungi had a different effect on the fermentation of straw diets. In comparison with UWS, in the TWS-PC diet dry matter (DM), organic matter (OM) ( P < 0.01) and acid detergent fibre (ADF) ( P < 0.05) degradabilities were increased. However, in the TWS-PX diet there were reductions in neutral detergent fibre (NDF) ( P < 0.001), ADF ( P < 0.05), hemicellulose (HC), and cellulose (C) ( P < 0.001) degradabilities, also in total and individual gas (methane and CO 2) production ( P < 0.001) in comparison with the UWS diet. The production of total volatile fatty acids (mmol day −1) was not influenced by the different straw diets. The production of total microbial matter and the efficiency of microbial proteosynthesis (g microbial N kg −1 organic matter fermented) were reduced in the TWS-PX diet ( P < 0.001 and P < 0.05 respectively) in comparison with the TWS-PC diet. The results indicate that the treatment of wheat straw with Polyporus ciliatus was more effective than the treatment of wheat straw with Lentinus tigrinus.