In situ degradability and gas production (GP) parameters of sweet sorghum and sweet sorghum bagasse silages compared with maize silage were determined in mini silos in order to compare the nutritional value of ensiled sweet sorghum and its bagasse with maize silage. Experimental treatments were 1) maize silages (MS) as control, 2) sweet sorghum silage (SS) and 3) sweet sorghum bagasse silage (BS) both supplemented with urea or molasses (10 and 50 g/kg dry matter (DM) basis, respectively). Triplicate silage samples were prepared for each treatment in laboratory silos for 90 days. The in situ degradability of DM and crude protein (CP) of fresh and 90-d ensiled forages were measured using three none lactating dairy cows fitted with rumen cannulae over 96 h. In vitro gas production was measured for 96 h and organic matter digestibility (OMD), metabolisable energy (ME) and net energy for lactation (NE_l) were estimated based on gas production parameters. Fresh sorghum and its bagasse had lower (P<0.01) ME, NEl and OMD than fresh maize. Fresh sorghum and bagasse had greater (P<0.05) immediately soluble fraction (a) of DM than fresh maize but for slowly degradable fraction (b) of DM opposite trend (P<0.01) was observed. The a fraction of CP in situ degradability of maize plant was greater than fresh sorghum and bagasse (P<0.01). Adding urea plus molasses increased (P<0.05) in situ a fraction of DM and CP and effective rumen degradability of DM and CP (P<0.01) in addition to ME and in vitro OMD for SS and BS which were rather comparable with MS. It seems that combination of urea and molasses as silage additives improves the nutritional quality of sweet sorghum and bagasse silages.