Recognition of the potential of whole crop wheat (WCW) as an ‘environmentally friendly’ complement to grass silage has led to several studies on its nutritive value. Most of these quantified nutritive value using the in vivo digestibility technique. In spite of the number of studies on the subject, there is little information available on the relationship between the digestibility and metabolisable energy (ME) content of WCW. The complications of measuring methane production have also meant that where reported, ME values for WCW have been estimated rather than measured. Accurate ME measurements are integral for the inclusion of WCW when formulating livestock diets. This study examined the relationship between digestibility in vivo and ME content derived using measured methane contents of WCW harvested at different stages of maturity and conserved using contrasting methods. The study forms part of an on-going MAFF LINK project that aims to develop equations for the laboratory-based prediction of the nutritive value of WCW.