Might be cheaper just to use big corks

Although probably just as unhealthy: "Norway Pauses Use of Fart-Reducing Cattle Feed in Wake of Danish Cow-tastrophe".

Denmark’s farmers have recently been reporting that their cows are collapsing and suffering illness after eating feed containing a methane-reducing additive called Bovaer.

Use of this feed is now legally required for many farms in Denmark as part of its national climate policy. Some farmers claim their cattle experienced severe symptoms after eating the additive-infused feed, including collapse, lethargy, reduced feed intake, fever, diarrhea, miscarriages, and significant drops in milk production.

Haven't they heard? Bill Gates has changed his mind and decided that climate change isn't really that big a deal after all.