About a dozen years ago, I was sitting in a conference next to John Waller, an Animal Nutritionist on the faculty at the University of Tennessee, Chattanooga. It was about the time that folks were in an uproar over the fact that government money had been spent for, of all things, measuring cow farts! John happened to have been one of the researchers on the project and we were laughing as he described the research and how he had explained to congressional aides what they had done, what they’d found, and why it was important.
Since then, we’ve all heard about dangerous methane in cow farts and burps and the potential for damaging the atmosphere. Research is ongoing into how to breed animals that burp less, forages we can feed them that reduce “emissions,” and there are even manure management tools that decrease greenhouse gases and allow us to use poop’s methane to produce electricity for farm use. Who would have thought there’d be so much effort related to bathroom humor, right?
What’s Up With Methane?
The primary reason folks are interested in methane output from ruminants is that, as greenhouse gases go, it’s much more efficient than other gases at trapping heat in the atmosphere. Though methane only makes up about 9% of our planetary greenhouse gas emissions, it traps 21 times more heat than carbon dioxide (CO2). (Nitrous oxide makes up about 5% of U.S. emissions and traps 300 times more heat than CO2. It comes from agricultural and industrial activities as well as from burning fossil fuels and solid waste.) Though scientists are still not positive how much methane is being produced by livestock, they estimate that “Enteric Fermentation” (a fancy term for what goes on in a ruminant) and management of their manure makes up about 32% of total methane emissions in the U.S. and cows are about 95% responsible for that 32%. That makes them relatively powerful, or as some folks might say “silent but deadly.”
All this flatus and eructation (farting and burping) is caused as rumen microbes turn forage into compounds that the animal can absorb. Methane is a by-product of this process. The more fibrous the forage, the more methane is produces. Grains are easier for the rumen to digest, so some have argued that the feedlot system that relies on grain rations is a better way to produce beef. But in a feedlot, it’s the manure that hits the methane fan. The large manure piles or lagoons created by feedlot systems create oxygen-free conditions and the bacteria working to decompose these piles of poop release methane. According to Animal Welfare Approved’s publication on this topic, A Breath of Fresh Air, the National Research Council found that “manure from animals fed with grain-based, high-energy diets is more degradable and has higher methane production potential than manure from animals fed with a roughage diet.”
So How’s That Planetary Destruction Going?
Numbers in the U.S. show that methane emissions have decreased about 8% since 1990. Unfortunately, the overall decrease is a result of changes in oil and gas production, and emissions from agriculture have actually gone up slightly. But never fear! New information is being produced as you read this, information on practices that will not only reduce emissions from your ruminants, but will also increase the efficiency with which they use the forages you feed them. We’ll share some of those discoveries in upcoming issues.
There are also the beneficial impacts of cattle grazing on greenhouse gases. Some of the most recent research in California is indicating that grazing can increase carbon sequestration in our soils. Last but not least, there are those making lemons out of lemonade, or electricity out of methane, such as dairies that use digesters to capture methane from manure to light up their barns and more.
So, though cattle and other ruminants may be contributing to problems we face, planetary destruction by cow farts is far from assured.
I certainly prefer the terms “flatus” and “eructation” in public discourse. Thank you.
Australian research has demonstrated that microbes in well managed pasture consume much more methane per day than the cattle produce, so methane production on pasture may not be problem at all.
I’ve found some info like that but I’d love to see what you’ve found too! Do you have a link or citation?
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