Yearly methane emissions of digestive origin by cattle in France. Variations with type and level of production

Abstract

Ruminants are sometimes accused of contributing greatly to the greenhouse effect due to their methane production of digestive origin. Daily methane emissions of most types of cattle were determined using respiration chambers. Animal methane emissions of digestive origin by dairy and beef cattle in France were calculated taking into account the various types and levels of animal production, variations in feeding regimen along the year and the number of bovines in each category in 1993.

Yearly methane emission by a dairy cow ranges from 140 to 160 m³ for milk yields ranging from 3400 to 6500 kg per year. Methane production decreases from 41 to 25 l/kg milk for the same range of milk yield. Yearly methane emission averages 120 m³ for a beef cow. It ranges from 56 to 78 m³ for growing dairy or beef cattle depending on type of production and growth rate. However, methane emission per kg carcass produced decreases when body weight gain increases. It ranges from 0.32 to 0.49 m³/kg for dairy cattle and from 0.58 to 1.04 m³/kg for beef cattle when the methane production of the dam over one year is included.

Total methane emissions by cattle in France were about 1.86 109 m³ in 1993, of which 38 % was produced by 4.6 million dairy cows, 6 % by dairy heifers (future breeding herd), 26 % by 4.0 million beef cows, 7 % by beef heifers (future breeding herd) and 23 % by 6.6 million growing cattle destined to meat production. Various means for reducing methane emissions by cattle and other sources are discussed.