The effect of chemical composition of silages on in vitro gas fermentation profiles in rabbits was examined. The study was performed using 7 silages: beans (Phaseolus vulgaris), faba bean (FB, Vicia faba), common vetch (CV, Vicia sativa), ryegrass (Lolium perenne), barley (B, Hordeum vulgare), barley with common vetch (BCV) and barley with faba bean (BFB). We used 3 New Zealand White (NZW) rabbits as donors of caecal content in each incubation run (n=3). Data were analyzed in a completely randomized experimental design. The CV silage showed higher values of crude protein (CP), followed by FB and bean silages (P<0.001). Barley silage had the lowest CP content (96g kg -1 DM) (P=0.001). The NDF and ADF content were lower (P<0.001) for beans and CV compared with the rest of the forage silages. Ryegrass silage had higher values of dry matter degradation, organic matter degradation, relative GP and SCFA (P<0.001). The highest values of digestible energy were for CV and bean silages (P<0.001). Ryegrass and CV silages showed higher levels in GP parameters, which could be associated with their better chemical composition characteristics, mainly pr otein and fiber content.