Individual data from dairy cows on CO2 emissions in respiration chambers and with GreenFeed will be contributed to a project by Aarhus University, Denmark (Peter Lund and Maria Kjeldsen) via the GRA Feed and Nutrition Network (see letter attached). The main aim of the project is to evaluate the equation of Madsen et al. (2010) (and develop new equation) for predicting CO2 production, which is widely used in combination with sniffer methods (CH4/CO2 ratio) to calculated g of CH4 per day. Advantage to NZ for providing data is that the new equation will also be relevant for NZ conditions and the information can be used for future trials where CH4/CO2 concentrations are measured to predict CH4 output. Data are coming from GreenFeed trials funded by NZAGRC and respiration chamber trials funded by the MPI inventory team. 