We conducted nitrogen balance trials for the project “Brassicas - a win-win option for GHG mitigation and animal productivity” under the SLMACC programme. The purpose of the trials was to determine nitrogen excretions from sheep fed forage rape. The data obtained from the trials contained digestibility measurements. Although a few digestibility trials with fresh forages have been conducted, no standard or verified protocol seems to exist. Thus, in addition to the analysis of our data for nitrogen balance, we also analysed the data in the aspect of how to optimise a digestibility trial with fresh forage. This manuscript can be regarded as a by-product of the project. The abstract of the manuscript has been approved (ROI 256)previously in the ROI system for submission. The abstract was accepted by the conference organiser and we were invited to draft a full manuscript. If this manuscript passes peer reviewing, it will be published in Animal Production Science.