Culturing bamboo with the white-rot fungus Ceriporiopsis subvermispora improved its nutritive value for ruminants. The bamboo substrate was prepared by grinding madake bamboo (Phyllostachys bambusoides) culm into a fibrous powder, mixing it with rice bran at an air-dry weight ratio of 19:1, then sterilizing the mixture at 118 degrees C for 40 min. After inoculating wheat grain spawn of C. subvermispora, the bamboo substrate was cultured at 28 degrees C for 10 and 15 weeks. For in vivo digestion, mixed bamboo substrate (MBS) cultured for 10 or 15 weeks was used. Three sheep were each assigned to a diet group in a 3 x 3 Latin square experiment and fed either a basal diet composed of alfalfa hay cubes, wheat bran and soybean meal (699:201:100, on dry basis), 303 g/kg of a basal diet replaced with bamboo or MBS. Organic matter (OM), neutral detergent fiber excluding residual ash (NDFom), acid detergent fiber excluded residual ash (ADFom), and lignin(sa) content of the bamboo substrate before inoculation decreased (P<0.05) following culture with C. subvermispora. The OM, NDFom and lignin(sa) content of the bamboo substrate cultured with C. subvermispora for 10 weeks were higher (P<0.05) than that of bamboo substrate cultured for 15 weeks. However, there was no difference in ADFom content of bumboo substrate between 10 and 15 weeks. The in vitro OM digestibility (IVOMD), in vitro NDFom digestibility (IVNDFomD), and in vitro gas production during 48 h of incubation (IVGP) increased (P<0.05) in the bamboo substrate following culturing with C. subvermispora. NDFom and lignin(sa) content of bamboo used in in vivo digestion were 905 g/kg DM and 198 g/kg DM, respectively. NDFom and lignin(sa) content of MBS were 703 g/kg DM and 106 g/kg DM, respectively. The IVGP and IVOMD of bamboo were 19 ml/g OM and 0.133, respectively, while those of MBS increased to 150 ml/g OM and 0.671. The coefficients of apparent OM, NDFom and ADFom digestibility of bamboo were 0.129, 0.127 and 0.149, respectively, while those of MBS increased (P<0.05) to 0.447, 0.495 and 0.527, respectively. We Suggest that C subvermispora is capable of improving the nutritive Value of bamboo that can then be used as a ruminant feed. (C) 2009 Elsevier B.V. All rights reserved.