The objective of the presented work was to compare different storage time influence on chemical composition, fermentation process, dry matter and neutral detergent fibre (NDF) rumen degradability and indigestible neutral detergent fibre content (INDF). Experimental grass silages made from four grass species were stored for 10 and 20 weeks. We didn’t find statistical significant differences for chemical composition and degradability parameters. However better values of rumen degradability parameters were found for 20 weeks old silages. Statistically significant differences (P < 0.05) were found only for lactic acid and acetic acid content, where higher amounts were detected for shorter time stored silages. Based on presented results we can claim that length of ensiling process has not negative influence on dry matter and NDF rumen degradability parameters of grass silages.