The aim of this study was to compare the effect of grass species on chemical composition and quality parameters of neutral detergent fibre (NDF) of grass silages. The potentially degradable fraction of NDF (b), rate of NDF degradation (c), effective degradability of NDF (EDndf) and indigestible NDF (INDF) were evaluated as quality parameters of NDF. The data were used for testing of prediction options of EDndf and INDF. The highest crude protein (CP) content (PO.05) was detected for fescue grass. Rye grass had the lowest content of NDF and acid detergent lignin (ADL). The highest values for parameter b, c, EDndf and therewithal the lowest INDF were found for rye grass. The ADL was the best single predictor using set of all tested silages (Revalues of 0.433 (EDndf) and 0.636 (INDF)). Using two predictors, the accuracy level increased. The combination of CP and ADL gave R2-values 0.597 and 0.808 for EDndf and INDF, respectively. However, better prediction equations were obtained using data for each grass species separately.