Grass-fed Angus cattle roam the pasture at Wholesome Living Farm in Winchester, Ky. It’s an appealing scene, but is grass-fed beef the best choice for the consumer, the animal and the planet? (Luke Sharett/Bloomberg)

Grass-fed beef is the meat of the moment. The image of cattle dotting green hillsides is an appealing counterpoint to the thought of herds corralled in crowded, grass-free feedlots. Advocates claim a trifecta of advantages: Grass-fed beef is better for you, for the animal and for the planet.

Is it?

[Vegetarian or omnivore: Which diet is better for the environment?]

First, let’s establish what we’re talking about. All U.S. beef cattle are started on grass, so “grass-fed” actually means “grass-finished,” or fed grass their whole lives. The USDA specifies that, to qualify as “grass-fed,” the animal has to eat “grass and forage” exclusively (after weaning) and must have “continuous access to pasture during the growing season.” It does not specify how much feed has to be from that pasture; hay and other harvested forage is allowed. (There are also third-party certification programs with varying criteria.)

Now, on to the questions.

Is grass-fed beef better for you?

It usually has higher concentrations of some nutrients: antioxidants, some vitamins, a kind of fat called conjugated linoleic acid (CLA) and the long-chain omega-3 fats mostly found in fish. It also has less fat overall.

Most health claims focus on the omega-3 fats, which are generally regarded as healthful. The other nutrients are less relevant, says Alice H. Lichtenstein, a professor at Tufts University’s Friedman School of Nutrition Science and Policy: Either their amounts are too small to be significant or evidence of their value is equivocal. (Read the research on CLA, for example, and you find that a lot of “further research is warranted” and “findings are inconsistent.”)

As to the omega-3s, we need to look at amounts. Omega-3 levels in grass-fed beef generally are about 50 percent higher than in regular beef. But because the levels in regular beef are so low, that’s not much of an advantage. Concentrations can vary widely, but according to the USDA, a 100-gram serving (a little under four ounces) of grass-fed top sirloin contains 65 milligrams of omega-3 fats, loin has 40 and rib-eye has 37. So even that 65-milligram amount is only about 22 milligrams more than that for regular beef and still far below levels in low-fat fishes such as tilapia (134 milligrams) and haddock (136). The omega-3 powerhouse king salmon has 1,270 milligrams. (The same logic applies to milk from grass-fed cows. It’s higher in long-chain omega-3 fats than milk from grain-fed cows, but a cup still has only 18 milligrams.) Recommendations on how much of these fats we need vary; most are in the range of 300 to 1,000 milligrams per day.

“Grass-fed beef is fine” says Lichtenstein, “but it’s not a good source of omega-3 fats.” Although it certainly has a better fat profile than standard beef, she says she’s concerned that a reputation for healthfulness will make people believe that it’s better for them than it is, which will lead to overconsumption.

The bottom line is that grass-fed beef is probably better for you, but only a little. Don’t hang your hat on it. If you like it (and not everyone does), by all means, eat it.

A grass-fed yearling bull. Experts differ over whether grass feeding is better than feedlots. (Charles McQuillan/Getty Images)
Is grass-fed beef better for the animal?

The answer is a resounding “it depends.”

I’m drawn to the idea of cattle grazing freely in fields. I’ve seen the pictures of the green hillsides, and I’ve seen the pictures of the muddy feedlots. I asked Temple Grandin, one of our foremost experts on animal welfare, whose work informs livestock systems across the country, whether grazing cattle are happier than feedlot cattle.

The first thing she said was, “grain is like cake and ice cream to cows,” and I can’t help thinking that eating something they find delicious contributes to the animals’ happiness. It certainly does to mine. But, just as it’s unadvisable for us to make cake and ice cream our sole ration, cattle shouldn’t be eating only grain.

“Grain is fine as long as there’s plenty of roughage,” says Grandin. Otherwise, the pH in the animal’s system can become too acidic, and that leads to all kinds of health problems. The idea that feeding grain to a ruminant, whose digestive system is fine-tuned for grass, leads to suffering is both right and wrong.

“The problem comes when you push too hard,” says Grandin. Animals grow faster on grain, she points out, so there’s a financial incentive for the rancher to up the grain ration. Like anything connected with the care of animals, feeding cattle grain can be done well or poorly.

Grandin talked about other issues as well. If the feedlot is dry, roomy and shaded, cattle are perfectly content. If it’s muddy, crowded or hot, they’re not. One of the keys to cattle happiness, it turns out, is drainage. “The feed yard should have a 2 to 3 percent slope to keep it dry,” says Grandin. Pastures can pose problems, too. “Cattle also really like to graze,” she says, “but that hillside when you have a blizzard is not so nice.”

The key to cattle’s well-being isn’t in the venue. It’s in the management. What’s maddening is that, when you’re standing in front of your market’s meat case, you usually can’t know which feedlot, or which pasture, the beef came from, let alone how it’s managed.

Is grass-fed beef better for the planet?

Here’s where things get really complicated. In general, beef is not planet-friendly. Cattle produce methane, a potent greenhouse gas, and beef routinely tops the charts of foods you should eat less of to curb climate change.

Grass-fed advocates maintain that well-managed grazing can offset or even completely compensate for methane and other greenhouse gases associated with beef cattle by locking carbon in the soil. The vegetation soaks up and stores, or sequesters, carbon, preventing carbon dioxide — another greenhouse gas — from being released into the atmosphere.

The operative phrase is “well-managed.” When poorly managed, grazing can degrade pasture, and scientists and ranchers are experimenting with various densities and grazing patterns to try to figure out which ones lead to more effective carbon sequestration.

According to Jason Rowntree, an assistant professor at Michigan State University who specializes in grass-eating cattle, some researchers have managed to sequester three metric tons of carbon per hectare, about 2.5 acres, per year. (Sequestering a ton of carbon is the equivalent of locking away 3.7 tons of carbon dioxide.)

But Rattan Lal, director of the Carbon Management and Sequestration Center at Ohio State University, sets expectations lower. He says one metric ton per hectare is a reasonable estimate of the maximum that grazing can sequester in a place like Ohio, where growing conditions generally are favorable, and a half-ton would be more realistic in drier areas. He supports grass-fed beef but says carbon sequestration “can’t completely compensate for the greenhouse gases in beef production.”

Weighing carbon sequestration against methane production is a dicey business, and I’ve read many different estimates. To get a back-of-the-envelope sense of how the two compare, I did the math. The methane produced yearly by a beef steer is approximately equivalent to the carbon sequestered in an acre and a half (at Lal’s one-ton-per-hectare rate). The steer’s methane isn’t the only issue, of course: The climate cost of each steer has to include a whole year’s worth of its mom’s methane, since cows have only one calf annually. Then there are all the other inputs, including what goes into growing and harvesting the hay the steer eats when pasture is unavailable. As always, it’s complicated.

I found little agreement on how much carbon well-managed grazing can sequester, but across-the-board agreement that it can certainly sequester some. But, diabolically, so can well-managed grain farming: Systems that use crop rotation, cover crops, composting and no-till also sequester carbon. If we’re comparing grass-fed with grain-fed, it’s only fair to assume excellent management in both systems.

There are a few other confounding issues. Cattle fed grain emit less methane and grow faster, which means they’re not alive — emitting methane — as long. Confining cattle in feedlots allows manure to be collected and fed to a digester, which converts it to energy — or, of course, it can leak out of badly managed facilities to pollute our water. In winter, bringing in harvested hay requires more energy than bringing in grain, because you need more of it. But grass-fed cattle turn a plant that humans can’t eat into high-quality people food, which is important in places where marginal land will grow grass but not crops. It’s a very mixed bag.

Some grass-fed cattle are better for the planet than some grain-fed, and vice versa.

Farmer Raymond Palmer raises grass-fed cattle in Lifford, Ireland. (Charles McQuillan/Getty Images)
The upshot

Where does that leave us?

Well, it’s left me a little less doctrinaire. Almost always, when I talk to scientists and farmers about food supply issues — whether it’s farm size, organic methods, animal welfare, GMOs, climate impact — the answer is complicated. When it comes to feeding people, there is never one right answer. It depends on the farm, the area, the animal, the crop, the weather, the market and a bazillion other things. Both Rowntree, who has spent years figuring out how best to graze cattle, and Lal, who has devoted a career to climate-change mitigation, are quick to tell me that grass-fed isn’t the only way.

“No matter what strategy you choose,” says Lal, “there are always trade-offs.”

What the grass-fed vs. grain-fed debate really tells us is how inadequate labels are to differentiate good from bad in our food supply. Yet those labels are regularly embroidered on flags and hoisted over intractable positions. Grass-fed beef is better! Buy organic! Only GMOs can feed the world!

What I wouldn’t give for a certificate of prudence, attesting to sound management, humane standards and responsible stewardship on any kind of farm. It’s worth working toward, and lowering the flags would be a good start.

Haspel, a freelance writer, farms oysters on Cape Cod and writes about food and science. On Twitter: @TamarHaspel. She’ll join Wednesday’s Free Range chat at noon: