We tested the hypothesis that improving sward structure through adjustments in forage allowance re-sults in greater forage intake and live weight (LW) gains by beef cattle and lower CH4emissions perunit LW gain and unit area in a native grassland ecosystem of the Pampa biome. The experiment wascarried out during 2012 and 2013 in southern Brazil.The experimental design was a randomized com-plete block with two replicates. Treatments consisted offive contrasting forage allowances of a nativegrassland managed under continuous stocking: 4, 8, 8–12, 12, and 16 kg of dry matter (DM) 100 kgLW−1day−1(or % LW). The 8–12% LW treatment had a variable forage allowance of 8% LW in springand 12% LW in summer, autumn, and winter. Forage allowance was controlled by changes in stockingrate (kg LW ha−1). Average daily gain (kg LW day−1) was high for forage allowances of 12 and16% LW but decreased at 8%, reaching the lowest value at 4% LW treatment (p<0.001).Liveweightgain ha−1year−1was the greatest at forage allowance of 8–12% LW (p< 0.001). Forage DM intakepeaked at a forage allowance of 12% LW (p= 0.005). Individual CH4emissions remained constantaround 150 g day−1for the two highest forage allowances and decreased to 118 and 107 g day−1under forage allowances of 8 and 4% LW, respectively (p= 0.002). Emissions per unit LW gain and unit area were driven by animal productivity changes and decreased with increasing forage allowance(p=0.001andp= 0.040, respectively). We propose that the combination of 8% LW forage allowanceduring spring and 12% LW during the rest of the year should be targeted to best balance animal produc-tion and environmental impact in the Pampa biome.