O'BRIEN: Ermias gave me a tour of the U.C.

Davis Dairy Teaching and Research Facility.

So these cows are doing their part for science, right?

-Yes, they're, they're helping us really investigate and try to reduce methane.

O'BRIEN: Ermias is leading a study with two dozen cows to measure how effective the active ingredient in Asparagopsis seaweed is at blocking methane.

He introduced me to some of his test subjects.

(chuckles, coos): Hello!

-Oh, yeah, they're very, very curious.

-Hello, how are you?

-They're a very curious bunch, yes.

-How are you?

Yeah.

-(laughs) -Holy cow, holy cow, I'd say, huh?

-Yeah, they like.

(chuckles) ♪ ♪ KEBREAB: This is our cold facility for weaned animals.

O'BRIEN: Ermias and postdoctoral fellow Paulo de Meo Filho showed me their research methods.

To gather data on how much methane a cow might be exhaling, they use a device called GreenFeed.

(cow licking) As the cows lick, chew, breathe, and belch, the gases they exhale are sucked into a tube for real-time analysis.

KEBREAB: So it will analyze the contents of the, uh, of the breath.

O'BRIEN (chuckling): Well, so much for that-- that's okay.

Don't worry about it, we'll just, we'll keep going here.

♪ ♪ O'BRIEN: They are recording impressive results.

Cows that consume just one quarter of one percent seaweed in their diet emit 30% less methane.

What do you think the upward limit is?

KEBREAB: In the literature, there is a report that 98% reduction.

-98?

-98% reduction.

Ourselves, we've seen about 80%.

O'BRIEN And that's with only one-half of one percent seaweed additive.

Cows perform a kind of biological alchemy, turning grass into milk and meat.

So, why does that generate so much methane?

♪ ♪ To understand that, we need to ruminate on the rumen, the first of four compartments in a cow's stomach.

Here, microbes start the whole process of turning grass into energy.

But this fermentation also releases carbon dioxide, CO2, and hydrogen, H2.

An enzyme called MCR converts those molecules into methane, CH4, and it is exhaled.

But this process can be disrupted by an ingredient in seaweed called bromoform, CHBr3.

It disables the MCR, preventing the CO2 and H2 from forming methane.

And the hydrogen is now available to create more energy for the cow.

♪ ♪ Ermias and his team routinely extract and analyze the DNA of rumen microbe samples.

DE MEO FILHO: So I'm using very little pressure.

He's doing all the work.

(device beeps) KEBREAB: Okay.

(murmurs) (de Meo Filho speaking off mic) O'BRIEN: He didn't seem to mind very much at all, did he?

KEBREAB: No, no, this is... -Didn't bother him a bit.

-No, no.

O'BRIEN: Yeah.

KEBREAB: This, this is what they do every week.

When we have inhibition of methane, we want to know what are the microbes that have been affected by reduced methane.

O'BRIEN: This is how they're identifying the genes that control methanogenesis, the microbial process that produces methane in the rumen.

It's a holy grail discovery.

If they can edit the DNA of these microbes, they could stop methane production permanently.

KEBREAB: So we will have, like, a probiotic.

O'BRIEN: So you could take a capsule.

-You take a-- exactly.

You can take a capsule.

-The gut biome gets edited.

-Yes, exactly.

-And for the rest of their lives... -That's it.

-...no more methane.

-No more methane, that's, you know... That's what they'll be hoping.

O'BRIEN: It's the long-term solution.

Hunting for these crucial genes is a laborious process that will take some time.

Seaweed in the cow feed can happen a lot sooner.

KEBREAB: It's a tool by itself.

O'BRIEN: Uh-huh.

-But it's also a tool to get us into a different way of, uh, of, uh, coming with a solution, as well.