Ruminants (cattle, sheep, goats) have the specificity of being able to digest grass – something that humans, for example, cannot do. They thus value land that cannot be plowed (steep, wet or stony, for example). Indeed, these animals have in their rumen (one of their 4 stomachs) bacteria which degrade cellulose: a very solid fiber of plants. This natural fermentation produces methane which is emitted by belching. Methane is a gas that contributes to the greenhouse effect. It corresponds to 5% of the greenhouse gases emitted in France. There is, in the current state of knowledge, little room for maneuver on the emission of methane linked to rumination but research is developing on animal nutrition or on the bacterial flora of the rumen.
Fortunately, in return, the grass of the prairies, consumed by ruminants (60 to 80% of their diet), captures the CO2 from the air and converts it into carbohydrates (plant tissues) through photosynthesis. When plants wilt, this carbon is integrated and stored sustainably in the grassland soil. In the end, most of the methane that the cows reject is offset by the storage of carbon in the soil of the meadows they graze.
Ruminant farming therefore makes it possible to conserve 11 million hectares of permanent meadows at national level which, if plowed, would release a large quantity of carbon into the atmosphere (1000 kg) of carbon per hectare per year).