A European startup has started selling carbon credits for cattle raised on a feed supplement that reduces the amount of heat-trapping greenhouse gas they release.

Mootral, based in Switzerland and the U.K., says its garlic-and-citrus feed can cut methane emissions from livestock by an average of 30%. Under its offset program, a certified farmer that¡¯s produced milk using Mootral¡¯s supplement can sell credits equal to one ton of carbon dioxide to customers that want to offset their pollution.

Livestock farming accounts for about 15% of global greenhouse gas emissions, largely from cows, sheep and other ruminants that emit methane, a gas that¡¯s more than 80 times more potent than carbon dioxide. Agriculture is making inroads into the $320-million voluntary carbon market, particularly through more environmentally friendly farming, though demand has so far been limited.