Biological de-lignification of straw by white-rot fungi seems a promising way of improving its nutritive value. The bio-conversion of lignocellulosic materials is circumscribed to the group of white-rot fungi, of which some species of Pleurotus are capable of producing upgraded spent-straws as ruminant feed (Fazaeli et al., 2004). Treating of cereal straw with white-rot fungi as animal feed was studied by several workers (Gupta et al., 1993; Zadrazil, 1997). However, most of the trials were conducted at in vitro stage and used cell wall degradation and in vitro digestibility as an index to evaluate the biological treatments. This experiment was conducted to study the effect of fungal treatment on the voluntary intake, in vivo digestibility and nutritive value index of wheat straw obtained from short-term and long-term solid state fermentation (SSF).