Methane emissions by livestock are responsible for 14.5% of the global emissions. The number can be actually higher considering that methane is 84 times more potent than CO2 in a 20-year span. Considering the net-zero targets for mid-century, 84x potency may be more relevant than 25x used to get the 14.5% figure. Although going vegan can help, there is slim chance that veganism can spread in such speed and scale that will put a big dent in time.

In that spirit, is there any cost analysis of how much changing diet of cows, or adding supplements to their food, can affect the methane they emit? One could also do selective breeding with the goal of reducing their methane emissions, but that would be slower than changing diet.

  • Do you have any reason to think methane is not normal for a ruminant digestive system? Apr 14, 2022 at 14:26
  • "normal" is a bit to broad. If you're asking "can methane be changed by diet?" So the methane is produced, or mostly produced, by the microbiome in the gut of a cow, which means answer is "yes". But if your question is "if we lower the emissions without negatively affecting the productivity (meat, milk, reproduction), the answer is I don't know. Apr 14, 2022 at 15:56

1 Answer 1


A number of sources claim that adding seaweed to the diet of cattle can reduce methane emissions from cattle by 70 to 86 percent.

Cows fed small amount of seaweed burp 86 per cent less methane in trial

Carbon farming: reducing methane emissions from cattle using feed additives

Alternatively, cattle fed high carbohydrate diets such are diets containing more corn than cellulose, such as hay or grass, produce less methane.

Methane emissions from cattle

In the U.S., domestic livestock contribute 36 percent of the methane humans cause to be put into the atmosphere.

Trials in the Netherlands that are showing promise in reducing cattle methane emissions are using garlic compounds with citrus and other additives.

Edit 30 June 2022

Latest news item. Methane-reducing seaweed asparagopsis up for sale after years of research

After years of frantic research and fast-tracked commercial licensing, cattle feedlots can now buy asparagopsis, a native Australian seaweed touted to reduce methane emissions by "90 to 95 per cent" when fed to cows and sheep.

Research suggests very little asparagopsis needs to be included in a ruminant animal's feed for its methane emissions to plummet.

"Say a cow's dry matter intake is 14 kilos a day,"Mr Main said.

"The amount of seaweed we'd need to give it is less than a squash ball — it's 50 grams."

  • amazing, thank you so much! Apr 15, 2022 at 14:11

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