The aim of this experiment was to evaluate the utility of CO2 production rate (CPR; g CO2/d) and animal weight (WT) data as proxies for feed-intake to adjust methane production rate (MPR; g CH4/d) in situations where dry-matter intake (DMI) is not known. This experiment measured individual-animal DMI, MPR and CPR in the feedlot, and then again on restricted quantities of grain and roughage diets in open-circuit respiration chambers. Of the 59 cattle tested in the feedlot, 41 had MPR and CPR recorded, and 59 and 57 had test results on the restricted grain and roughage rations. Methane production relative to DMI by individual animals was calculated as methane yield (MY; MPR/ DMI) and as residual methane production (RMPDMI; calculated as MPR less predicted MPR based on DMI). A second form of residual methane production:RMPCO2, was calculated by regressing MPR against CPR to determine whether animals were producing more or less CH4 than predicted for their CPR. Carbon-dioxide production rate was positively associated with DMI in all 3 test phases (R2=0.25, 0.45 and 0.47; all P