This experiment was done to evaluate in vivo greenhouse gases production, nutrient utilization and rumen parameters affected by silages in diets of sheep from Feb to May, 2018 at Can Tho University farm. Four male sheep with average live weight of 17,3±1,48 kg were arranged in a 4x4 Latin square design with 4 treatments including (1) Paspalumatratum (PA), and (2) 40% Pennisetumpurpureum silage (PPS40), (3) 40% Operculinaturpethum silage (OTS40) and (4) 40% Psophocarpusscandenssilage (PSS40) replacing Paspalumatratum (%DM) in the diets. Methane and carbon dioxide were measured by using the chambers for 2 continuous days and analyzed by a Greenhouse Gas Analyser (USA). The results showed that the CH4 production (g/kg OM intake) of sheep was significantly different among the treatments (P4 production (g/kg OM intake) of the OTS40 treatment (6.37) was the lowest, following by the PSS40 treatment (6.93), the PPS40 treatment (7.69), and the PA treatment (9.60). The metabolizable energy (ME) intake was improved by the silage diets (P=0.056), while digestible protein intake and nitrogen retention of the OTS40, PSS40 PPS40 treatments tended to be higher than that of the PA treatment (P>0.05). Daily weight gains (g/day) of sheep were likely to be higher (P>0.05) for the OTS40, PPS40 and PSS40 treatments. The conclusion was that replacing Paspalumatratum grass by PPS, OTS or PSS at level of 40% (DM) in diets reduced CH4 output, tented to improve total DM intake, crude protein digestibility, rumen parameters and nitrogen retention and reduced CH4 output of growing sheep. Keywords: methane, nitrogen retention, nutrient digestibility, sheep, silage.