Les gaz à effet de serre en élevage bovin: Évaluation et leviers d'action

Abstract

In today's environmental context, as much political (the reduction of greenhouse gas emissions) as social (consumer demands for information concerning food products), there is a need to determine the influence of ruminant livestock on climate change. It has become crucial to quantify precisely the levels of greenhouse gas emissions (GHG) and carbon sequestration for different ruminant livestock systems by using Life Cycle Assessment (LCA) to calculate the carbon footprint of dairy and beef farms. This approach allows us to account for GHG in relation with direct and indirect emissions. Thus in the French dairy system, the average gross carbon footprint is 1.26 kg CO 2 /kg milk. Carbon sequestration under grassland and hedges compensates for GHG emissions ranging from 6 to 43% according to the system utilized. Consequently the net carbon footprint is 1.0 kg CO 2/kg milk. In the French beef system, the gross carbon footprint for raw materials is comprised between 14.8 and 16.5 kg CO 2/kg of live meat depending on the production system. It must be mentioned that carbon sequestration represents compensation in a range of 24 to 53% and the net carbon footprint is between 7.9 and 11.3 kg CO 2/kg of live meat. These investigations demonstrate that numerous mitigation actions have been identified in the livestock systems to reduce the carbon footprint of milk and meat at the farm gate. Some of them concern management practices (adjustment of dietary intake, fertilization management...) which result in substantial savings in agricultural expenses. Others require the installation of new technologies which would require additional funds to improve the production processes.