Methane is one of the factors involved in the greenhouse effect. As ruminants produce methane in the rumen and eruct it, the aim of this study was to perform a global statistical approach on the data published by the Rowett Research Institute on male castrated sheep. This work underlined big variations between and within feeds for gross energy losses as methane. Lignin was the best predictor of methane losses, and a model including digestible energy and chemical parameters explained 90 per cent of methane variation. This work agrees with previous reviews on gross energy losses as methane and gives new information about the intrinsic feed influence.