A global emissions source database called EDGAR has been developed jointly by TNO and RIVM to meet the urgent need of atmospheric chemistry and climate modellers and the need of policy-makers. The EDGAR database was to estimate the annual emissions of direct and indirect greenhouse gases (CO2, CH4, N2O; CO, NOx, non-methane VOC; SO2), including ozone-depleting compounds (halocarbons) for 1990 on a regional and grid basis. To meet the aim of establishing the global emissions from both anthropogenic and biogenic sources, a complete set of data would be required to estimate the total source strength of the various gases with a 1x1 degree resolution (altitude resolution of 1 km), as agreed upon in the Global Emissions Inventory Activity (GEIA) of the International Atmospheric Chemistry Programme (IGAC) Methane production from herbivores is a by-product of enteric,fermentation, a digestive process by which carbohydrates are broken down by micro-organisms into simple molecules for absorption into the bloodstream. Both ruminant (e.g. cattle, sheep) and non-ruminant animals (e.g. pigs, horses) produce CH 4 , although ruminants are the largest source (per unit of feed intake).