In October 2007, the USDA released guidelines for raising grass-fed beef. The American Grassfed Association (AGA) wasn’t happy.

The USDA guidelines allow beef cattle to be treated with antibiotics and hormones, confined to the indoors (for at least part of the year), and fed grain before slaughter. The AGA, a national group of producers headquartered in Denver, has a different definition of “grass fed.” Products bearing the AGA label come from livestock fed a 100% grass and grass-hay diet. There are no vague “access to pasture” clauses that allow producers to withhold cattle from pasture during the offseason. There is no “incidental supplementation” (corn feeding) permitted.  The AGA seal denotes a real grass-fed, grass-finished product.

Loose definitions, high costs, and a dearth of producers make grass-fed beef tough to source. Is it worth the effort? Only if you’re into good taste, humane animal husbandry, and the environment. (Yes, it is!).

True to its cowboy tradition, the US is today the world’s largest beef producer. Our prodigious output of beef is made possible by corn-feeding, which, as Michael Pollan says, allows cattle to gain weight quickly but results in sick animals. These animals, who evolved to eat grass, need antibiotics to stay alive on their diets of corn and other grains. This is why grain-fed beef tastes nothing like grass-fed.

Grain-fed beef is marbled with fat, from which the product derives its flavor. Grass-fed beef is leaner. Its flavor is drawn from the various grasses and flowers on which the cattle feeds. As a result, the flesh tastes meatier and mineral with a flavor approaching gaminess. Visually, grass-fed appears more robust on the plate. Moreover, it has more omega-3s, Vitamins A and E, antioxidants, less cholesterol, and other nutritional advantages over grain-fed.

According to a Union of Concerned Scientists report, beef cattle account for 2.2% of greenhouse gas emissions. The report says the, “Use of pasture management practices that improve the nutritional quality of forage crops could reduce methane emissions from pasture beef by 15 to 30 percent.” This report is corroborated by a recent USDA report. Additionally, the energy that goes into raising corn and slaughtering cattle on CAFOs isn’t expended when cattle simply graze on wild grass. The USDA report even argues that grazing cattle improve the health of pastures if managed properly.

So, it’s clear that grass-fed and finished beef has some advantages over grain-fed. But a 100% grass-fed diet is often unrealistic. Cattle may need more than grass to get through the winter—sometimes they are fed wet hay, known as balage, or a mixture of grains like corn, barley, and oats. Often, cattle are fattened on grain for a few weeks before slaughter. The aim here is to produce marbling, which, corn-feeding being the norm for so long, most consumers have come to expect. (Let’s not forget–there’s more to steak than fat content.)

Two weeks of grain-feeding is  a barely perceptible echo of what happens on a feedlot, where cattle are finished on high volumes of grain for up to six months before slaughter. Keep theses differences in mind when dialing up beef. A little grain has its place. But not as the basis for the cattle’s diet.