What are they feeding that cow?

“Organic,” “natural,” “Biodynamic,” “grass fed,” “free range.” Those are some of the labels found on beef packages these days. But their ability to help you minimize your risk of mad-cow disease varies widely.

Two labels, organic and Biodynamic (trademarked), provide a reasonably reliable guarantee that the beef comes from the animals least likely to carry the disease. Those cattle were never fed certain animal by-products--blood, organ parts, and nerve tissue--that are the chief means of transmitting this brain-wasting illness. But you may have to shop outside your supermarket to find beef with those labels.

Both labels describe farming methods that ban animal by-products in cattle feed. The ban is enforced via inspections by independent parties: the U.S. Department of Agriculture for organic, and the Demeter Association, a private nonprofit group, for Biodynamic, an organic farming method that uses some spiritual principles.

In addition, some national beef brands, including Coleman Natural Beef, Meyer Natural Angus, and Niman Ranch, say in their literature and on their Web sites that their cattle are raised on all-grain diets. While we have no reason to disbelieve those claims, they’re not independently verified. The claims “100 percent grass fed” and “grass fed only,” which may appear on other companies’ packaging, would be useful if true, but they’re not verified, either.

A proposal by the USDA for an optional verification program for “process claims,” including feeding methods, would only add to the confusion. Products that passed an inspection could carry a “USDA Process Verified” shield next to the label “grass fed” if as little as 80 percent of the feed were grass, with no limits on the other 20 percent; “grain fed” could be used with a diet of as little as 50 percent grain. The agency has delayed implementation of the rule after protests from farmer and consumer groups, including Consumers Union, publisher of Consumer Reports magazine.

The terms “free range” and “natural” are less helpful. “Free range” merely means that the animal was not confined to a feed lot. The label says nothing about what it was fed. The USDA defines “natural” as “minimally processed,” with no preservatives or artificial ingredients. But that applies to all raw beef cuts, since they’re never processed.

For more about meat labels and mad-cow disease, go to www.eco-labels.org .