The Effect of Pleurotus spp. Fungi on Chemical Composition and in vitro Digestibility of Rice Straw

Abstract

This study was carried out to test the potentially of using rice straw substrate for the cultivation of four Pleurotus species including Pleurotus florida, Pleurotus djamor, Pleurotus sajor-caju and Pleurotus ostreatus and the effect of these species on the chemical composition, cell wall degradation and digestibility of rice straw. Rice straw soaked in water for 24 h and then it was pasteurized at 100 degrees C for 6 h. Rice straw was inoculated with spawns of four Pleurotus fungi (Pleurotus florida, Pleurotus djamor, Pleurotus sajor-caju and Pleurotus ostreatus) and packed in the plastic bags and incubated in a fermentation chamber at 23-27 degrees C and 75-85% relative humidity. After 60th day, rice straw samples from all groups were taken and analyzed for chemical composition and in vitro digestibility. The data obtained were analyzed according to the complete randomized design model consisting of four treatments plus one control and four replicates. The results of this study showed that fungal treatment increased (p<0.05) the Crude Protein (CP), silica, Ca and P contents of the rice straw but the hemicellulose, Organic Matter (OM), Acid Detergent Fiber (ADF), Neutral Detergent Fiber (NDF) and Acid Detergent Lignin (ADL) contents decreased. However, the ability of the fungi to degrade these components varied among the species. The ability of Pleurotus sajor-caju and Pleurotus ostreatus were higher than the other species in decreasing the hemicellulose, NDF, ADF and ADL contents. The highest Biological Efficiency (BE) was produced by sajor-caju species with 56.02 and the lowest was belong to Pleurotus djamor species with an average 51.17%. All species of fungi incubated on rice straw showed increased (p<0.05) the in vitro dry mater and organic matter digestibility. Rice straw treated with sajor-caju fungus had the highest in vitro dry matter digestibility (IVDMD) and in vitro organic matter digestibility (IVOMD) with 80.10 and 82.18%, respectively. In general this experiment cleared that treatment with sajor-caju can improve the quality of rice straw to be useful feed for ruminant nutrition.