A study was conducted at Can Tho University to evaluate the effects of higher soluble carbohydrate sources and supplementatal levels on the in vitro CH₄, CO₂ production and nutrient digestibility. The experiment was a factorial design (3x5) with 3 replications, the first experimental factor was feed sources with higher soluble carbohydrate (corn, broken rice and cassava chip), and the second was the supplemental levels of feed with higher soluble carbohydrate at 0, 15, 30, 45 and 60% (on DM basis) in the basal diet ofPara grass (Bracharia mutica). The results shown that the total gas, CH₄ and CO₂ (ml) production at 72 h were significantincreasing (P4 production (ml/g DOM) was significantly reduced from 30% (72.2 ml/g DOM) to 60% (66,9 ml/g DOM) (P4production (ml/g DOM) at 72 h was found 84.1, 91.4, 88.7, 85,6 and 84.4 in the treatments of 0, 15, 30, 45 and 60% with higher soluble carbohydrates sources, respectively. It was concluded that the CH₄ and CO₂ production (ml/g DOM) was lowerin the broken rice as compared to those in the corn and cassava chip.There was a reduction of greenhouse gas emission at 24 h by increasing levels of high soluble carbohydrate feeds from 30-60%, however the CH₄production at 72 h was significantly increased from 15-45 %. There was no significant difference between supplemental level of 0% and 60 %.