Cow burps are a major contributor to climate change — can scientists change that?

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• Christopher Booker:

  At the University of California at Davis – 18 cows are cordoned off from others on the campus's dairy facility. They are part of an ongoing series of studies to dramatically reduce the climate impact of dairy and beef production.

  Globally, cows and other livestock animals are responsible for about 40 percent of methane emissions – a potent greenhouse gas. In digesting their high fiber diet, cows emit methane as a byproduct, making them one of the least climate friendly sources of food on the planet.

• Ermias Kebreab:

  The idea was to try to see if we can do something about the way in which the methane is being formed by giving them some additives.

• Christopher Booker:

  Ermias Kebreab is a Professor at UC Davis, and he has been studying how dietary supplements affect the amount of methane a cow emits, almost all of which comes out of its front end.

• Ermias Kebreab:

  About 89 nine percent of the methane has actually been formed in the gut of the animal. And almost all of that is then irradiated out or belched out of it from the animal. So the nostrils and the mouth. We don't care about the back end.

• Christopher Booker:

  Kebreab's research has shown that it doesn't take a lot to dramatically alter the amount of methane burped out. In a study that was published last year, his lab found that adding just 3 ounces of seaweed each day reduced methane emissions by 82 percent.

• Ermias Kebreab:

  I've been in this business for about 20 years or so, so having this amount of impact, it completely blew my mind and I didn't even believe when I saw the results at first. I did not expect it at all.

• Christopher Booker:

  Those results have since been replicated, and Kebreab's lab is now testing other kinds of methane-reducing additives that have shown promise in lab tests.

• Mallory Honan:

  Cows are creatures of habit, so they don't like it when you change things on them.

• Christopher Booker:

  Mallory Honan is a doctoral student at UC Davis, and running this 12-week experiment testing a new microbial probiotic additive called Amplio.

• Mallory Honan:

  We sample their milks as well as their blood. I weigh them weekly just to make sure that we're not compromising any of their important production parameters because if we feed an additive that reduces methane, but then it compromises all these components that the farmers are paid for, but it's not really actually helping.

• Christopher Booker:

  Measuring the methane requires a special stall called a GreenFeed Machine – that delivers little treats, called cow cookies. While the cow is inside this stall eating, data on methane, carbon dioxide, and hydrogen are collected.

• Mallory Honan:

  They have access to the GreenFeed all the time because methane isn't emitted at a constant rate. So if you measured methane from a cow, right at this moment, that's not necessarily what she's emitting all day because it's very much linked to their feed intake. So we want to be measuring methane over a twenty four hour scale and getting as many data points as possible.

• Christopher Booker:

  Testing the impact of these additives requires meticulous control of the cow's diet. Each animal's total feed is carefully measured and electronic collars ensure that each goes only to its own stall. The additive being studied – and a control placebo – are also carefully measured.

• Mallory Honan:

  These trials are really proof of concept to make sure that they're eating the full dose and that we're seeing the effects from that full dose. Because when you scale this up and go to a bigger commercial farm, they're not going to be able to measure everything. So individually, we're going to be seeing everything at a herd level. So this is our opportunity to see the effects that it has on an individual cow.

• Christopher Booker:

  While many of these additives are not commercially available yet, Kebreab hopes the costs will be minimal, and might even be offset by farmers selling carbon credits for the amount of greenhouse gas emissions reduced by the supplements.

• Ermias Kebreab:

  In California, we are even especially incentivized because we have on the books on legislation to reduce methane emissions by 40 percent by 2030.

• Christopher Booker:

  Kebreab says interventions like the ones he is studying are key to feeding the world, without worsening climate change.

• Ermias Kebreab:

  There's always going to be more demand. I mean, particularly in low-income countries, the demand is growing. So we're trying to come up with solutions that is applicable around the world and try to sustainably produce animal source food. So solving this or reducing is significantly by additives, by different methods that would really help us into going into a carbon-neutral livestock production system