Steers (12) previously screened using the SF₆ measurement technique and found to have either high or low methane yield (MY: gCH₄/MJ DEI) were re-tested on the same diet. Several steers changed their MY, but the group characteristic of High (1.3 g/MJ) or Low (0.8 g/MJ) MY persisted between the measurement periods as did differences in propionate concentration and protozoal density. This suggests that one or more innate animal attributes must affect MY. The need to consider intake variation of cattle in extrapolating short term measures of methane measurements to annual emission estimates was also highlighted.