Assessment of enteric methane emissions by farm animals in France in 2007

Abstract

Enteric methane accounts for 45 and 65% of total methane emissions, and is responsible for about 5% of global warming in France. The objective of the present paper was to update the annual enteric methane emissions by farm animals of the various categories in each involved species in France according to the recommendations of IPCC 2006 (Tier 3). Methane emissions have been assessed using the net energy requirements of animals converted to Metabolisable Energy Intake (MEI), and conversion factors (Y’m = kcal methane per 100 kcal MEI). Conversion factors and emission factors (kg methane/animal/y) were computed for the various species and categories of animals. The emission factor averaged 117.7 for dairy cows yielding 6300 kg milk/y, and ranged from 90 to 163 when milk yield increased from 3500 to 11 000 kg/y. It averaged 86.7 for beef cows, and 43.0 for ruminant growing cattle. The corresponding values were 14.4 and 11 for dairy and suckling ewes, 14.3 for goats, 20.7 for equines and 0.8 for pigs. Total enteric methane emissions in France amounted to 1.41 million tons. Dairy cows, beef cows and growing cattle contributed for 32 - 25 and 34%, respectively, to total methane enteric emission. Contributions of sheep, goats, equines and pigs were 6.2, 1, 1.5 and 0.8%, respectively, of total enteric methane emissions.