Benchmarking of greenhouse gas emissions of bovine milk production systems for 38 countries

This study quantifies and compares greenhouse gas (GHG) emissions of bovine milk production systems in 38 countries representing 70% of the world's bovine milk production. The analysis was based on the International Farm Comparison Network (IFCN) concept of typical dairy farms and the related globally standardized farms representing 45 dairy regions in 38 countries. Various concepts and coefficients from the literature were used to estimate GHG emission from each farm, and the IFCN software TIPI-CAL was used to conduct a partial life cycle assessment of GHG emissions from dairy production. This approach is seen as a first step towards a global comparison of GHG emissions from various dairy farming systems. Results show that GHG emissions at the farm level are 80 to 307kg CO₂-eqv 100/kg of energy corrected milk (ECM), and are lower in developed than in developing countries. Differences were mainly due to the level of intensity (i.e., milk yield/cow) in milk production. Enteric CH₄ emissions comprised the highest proportion of GHG emissions. Enteric and manure related emissions accounted for 70-95% of total emissions farms depending on farming system. Comparison of various estimators for enteric CH₄ emissions suggests that these values might be underestimated. Therefore, in future research, dairy farms should be categorized into farming clusters based on their production intensity and feed usage, with equations to estimate enteric CH₄ emissions specific to cluster. This article is part of the special issue entitled: Greenhouse Gases in Animal Agriculture - Finding a Balance between Food and Emissions, Guest Edited by T.A. McAllister, Section Guest Editors; K.A. Beauchemin, X. Hao, S. McGinn and Editor for Animal Feed Science and Technology, P.H. Robinson.