Wednesday, December 02, 2020

Adding seaweed to cattle diets can significantly reduce their impact on global warming

I had read about this before, but neglected to comment on it. However, it could be kind of a big deal in the fight against climate change which, although you may not realize it from a quick perusal of news feeds, is still ongoing.

Methane from livestock burps and farts makes up a surprisingly large element of our greenhouse gases. There are, after all, about a billion cows worldwide, and it is cows (and specifically the way they repeatedly burp up already-eaten food and chew it up as cud in order to digest it) that are the main offenders here. Other domesticated ruminants like sheep and goats also burp for the same reason, but have a much smaller "methane footprint" than cows. Cow farts are also a contributor of methane to the  atmosphere, but to a much smaller degree (about 5%) than their burping.

Methane is not as well-known a greenhouse gas as carbon dioxide, but it is a much more powerful one, warming the earth 23 times (or over 80 times, depending on what you read and the time frame used) as much as a similar volume of carbon dioxide, even if it is shorter-lived in the atmosphere. All in all, agriculture accounts for about 14-18% of greenhouse gases (although the calculation is somewhat fraught and contentious, especially when we are combining the effects of different gases) and the burps of ruminants make up a good proportion of that. By some estimates, about 5% of all greenhouse gases are due to cow burps alone.

So, anything that will help reduce the amount  of methane cows produce will help, and could help a lot. Not eating cows would definitely help, and that is starting to happen, especially in this age of Beyond Meat and Impossible Burgers (most of which are actually eaten by meat-eaters).

But the impetus for writing this article is the finding that adding a very specific kind of seaweed to a cow's diet can very significantly reduce the amount of methane it produces. There has already been some research on adding garlic to cattle diets, which decreases their flatulence to some extent, but adding some tropical red seaweeds (specifically asparagopsis armata and asparagopsis taxiformis) can have a huge effect on the way a cow digests its food. In one study, adding just 2% of a. taxiformis to their food reduced methane emissions by nearly 99%. Another study yielded a 95% reduction in methane by replacing 5% of the diet with red seaweed.

The red seaweed effect works through a compound called bromoform, which inhibits the action of an enzyme that produces methane during a cow's digestion, although it is not really well understood why this particular type of seaweed works so well. Studies are ongoing to ensure that the seaweed remains effective in real-world applications, that is shelf-stable, and is not unduly affected by heat and light. But seaweed farms to commercially develop the crop are already springing up in Australia and elsewhere.

Bear in mind, though, that much more methane is produced by the oil and gas industry and decay in landfill dumps than cows ever will. It helps to keep these things in perspective.

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