Inside the University of California, Davis, a Holstein cow has its head and neck sealed airtight inside a large, clear-plastic chamber that resembles an incubator for newborns. While giant tubes above the chamber pump air in and push air out, the cow calmly stands and eats her feed. Equipment inside a nearby trailer spits out data.
This is how and ultimately contribute to global warming. Quantifying these emissions is key to mitigating them, and Mitloehner is one of several 嘿嘿视频 researchers investigating economical around the globe.
READ MORE: Unfold, the official 嘿嘿视频 podcast, examines the bad rap cattle receive as an unfriendly producer of climate-changing greenhouse gas.
Cattle are the No. 1 agricultural source of greenhouse gases worldwide. Each year, a single cow will belch about 220 pounds of methane. in warming the atmosphere, said Mitloehner, a professor and air quality specialist in the .
With the , that fact has advocates urging the public to eat less beef. They contend it鈥檚 an unsustainable diet in a world with a population expected to reach nearly 10 billion by 2050.
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Mitloehner has openly challenged this view, writing in that 鈥渇orgoing meat is not the environmental panacea many would have us believe.鈥
Cows and other ruminants account for just 4 percent of all greenhouse gases produced in the United States, he said, and beef cattle just 2 percent of direct emissions.
Better breeding, genetics and nutrition have increased the efficiency of livestock production in the U.S. In the 1970s, 140 million head of cattle were needed to meet demand. Now, just 90 million head are required. At the same time, those 90 million cattle are producing more meat.
鈥淲e鈥檙e now feeding more people with fewer cattle,鈥 Mitloehner said.
The global problem
Shrinking livestock鈥檚 carbon hoofprint worldwide is a big challenge. .
India, for example, has the world鈥檚 largest cattle population, but the lowest beef consumption of any country. As a result, cows live longer and emit more methane over their lifetime. In addition, cows in tropical regions produce less milk and meat, so it takes them longer to get to market.
鈥淚f you have hundreds of millions of cattle to achieve a dismal amount of product, then that comes with a high environmental footprint,鈥 Mitloehner said.
Researchers at 嘿嘿视频 have projects in Vietnam, Ethiopia and Burkina Faso to boost livestock productivity through better nutrition. That may be critical going forward as demand for meat is rising in developing countries.
"We expect by 2050 there is going to be a 300 percent increase in beef demand in Asia," said Ermias Kebreab, a professor of animal science and director of the .
A new diet
Kebreab, Mitloehner and other 嘿嘿视频 scientists are looking for ways to make cows more sustainable and less gassy. One way to do that is to make their high-fiber diet easier to digest, so scientists often turn to feed supplements for this purpose. It sounds simple, but finding an affordable and nutritious additive has proved difficult.
However, Kebreab has succeeded in finding such a supplement by feeding dairy cattle a plant way off the trough menu: seaweed.
鈥淲e鈥檝e done one trial and showed that there is up to a 60 percent by using 1 percent of seaweed in the diet,鈥 Kebreab said. 鈥淭his is a very surprising and promising development.鈥
In addition to reducing methane output, the seaweed doesn鈥檛 make the cows鈥 milk taste bad. He鈥檚 now testing the diet on beef cattle. It could be a relatively inexpensive solution for reducing emissions.
This type of red seaweed, called Asparagopsis taxiformis, has one big drawback: a wild harvest is unlikely to provide enough of a supply for broad adoption. Other scientists are looking for ways to grow it to scale, and Kebreab remains hopeful that feed additives hold the most promise.
鈥淚 believe that we will have a solution, two or three good candidates, that would reduce emissions quite substantially,鈥 Kebreab said. 鈥淚 can see that happening in the next few years.鈥
Cows as part of the climate change solution
Besides emitting greenhouse gases, another common criticism of beef production is that cows take up nearly half the land in the United States. Overgrazing those lands can degrade soil health and biodiversity. Yet researchers argue that, managed correctly, cows help restore healthy soils, conserve sensitive species and enhance overall ecological function. Proper cattle grazing management can even help mitigate climate change.
On the Van Vleck Ranch east of Sacramento near Rancho Murieta, Jerry Spencer manages about 2,500 cattle. A good winter鈥檚 rain this year has left them a feast of green pastures. Spencer pays close attention to the grasses, making sure the animals have enough to eat but don鈥檛 overgraze. He maintains a diversity of native grasses to keep the cows healthy and rotates herds between pastures to give the plants a rest from grazing and opportunity to recover.
鈥淵ou want to leave as much as grass as possible to allow water infiltration and healthy root systems,鈥 Spencer said.
(Research at 嘿嘿视频 indicates just a touch of the ocean algae in cattle feed could dramatically cut greenhouse gas emissions from California鈥檚 1.8 million dairy cows.)
Maintaining healthy root systems isn鈥檛 just good for the plants. The longer and denser the roots, the more they can hold atmospheric carbon in the soil.
鈥淥ne of the best and most simple things we can do on rangelands to help mitigate climate change is to conserve rangeland ecosystems and keep the carbon that鈥檚 already stored in rangeland soils safely stored there,鈥 said Ken Tate, a 嘿嘿视频 rangeland watershed management extension specialist. California is at particular risk of rangelands being converted to housing and other developments, he said.
Ranchers really have little financial incentive to let their herds overgraze or let their herd鈥檚 hooves compact and degrade soils. Spencer said if the land degrades, then the cattle鈥檚 health can suffer as well.
鈥淪ustainability is keeping everything viable both economically and biologically,鈥 said Spencer. 鈥淩anchers don鈥檛 continue to exist if either one of those are really out of balance.鈥
While sustainable grazing practices won鈥檛 eliminate methane produced by the cows, they can offset it. According to , this solution could sequester 16 gigatons of carbon dioxide by 2050.
鈥淧roper grazing sustains working landscapes that support communities, food production and a healthy environment,鈥 Tate said.
Meat-free movement
Environmental considerations may factor into people鈥檚 food choices, but those decisions are also based on religious and cultural beliefs and traditions, as well as personal tastes. In low-income countries, there may not be any choice. It鈥檚 why Tate and Mitloehner believe the meat-free movement can go only so far.
鈥淭here will never be a situation where some major part of our diet will be ruled out,鈥 Mitloehner said. 鈥淢y job is not to judge people for their eating habits. My job is to look at how we can produce livestock and minimize those environmental impacts that do exist.鈥
Media contact: Amy Quinton, 嘿嘿视频 News and Media Relations, 530-752-9843, amquinton@ucdavis.edu
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