It’s not quite a stampede, but public-health concerns arising from the discovery of mad cow disease is fueling a marketing bonanza for organic and natural beef.

At the Community Mercantile Co-op, 901 Iowa, sales have increased about 25 percent since the first U.S. case of the brain-wasting disease was announced late last month. Here, like nationwide, producers of organic beef are having a tough time keeping up with demand.

“Sales seem to be going up,” said Tom King, the Merc’s meat department manager. “There’s really more questions than sale spikes. People are wondering, people are questioning how safe the meat is.”

The Merc is having a hard time keeping natural beef on the shelves, he said. The store’s weekly delivery usually arrives Fridays, but this week’s shipment was early and bigger than usual.

Good Natured Family Farms, based in Bronson, is the sole natural beef provider for the Community Mercantile. Good Natured’s beef is produced without growth hormones or subtheraputic antibiotics.

It’s struggling to keep retailers supplied.

“Our sales have increased,” said Diana Endicott, the farms’ market coordinator. “Prior to this we already had planned to do a promotion with Hen House. Coincidentally (mad cow) happened at the same time. It’s been a double whammy.”

The reason for the increase: Naturally raised cattle are less likely to contract mad cow, experts say, because their feed does not include high-protein animal waste and blood sometimes used to supplement nonorganic animal feed.

That material itself is not known to transmit the disease, but because animal remains are added to the feed, some experts worry unsafe neurological material that can carry mad cow could find its way into the feed.

Thomas Simmons, lead meat cutter at the Community Mercantile Co-op, arranges cuts of naturally raised beef at the store, 901 Iowa. Simmons said Thursday that natural beef had become a hot-seller since the U.S. mad cow case was reported in late December.

While a 1997 law prohibits cattlemen from feeding their animals food that contains brain and spinal cord tissue, feed that is often linked to the spread of the disease, enforcement is weak.

“All-natural meat is grass fed or vegetarian raised, so I can safely tell (customers) this is the cleanest meat available,” King said.

Endicott said her company’s beef comes from 30 farms in the Kansas City area where ranchers have control over the animals from birth to slaughter.

“They can track the meat, they have complete control over their diet, and the way they’re killed,” she said. “It’s a much easier product to control than commercial beef.”

Most beef cattle are transported to as many as four different farms and factories in their lifetime. And they often are rushed through without individual care or inspection. Organic farmers rarely slaughter cattle that are sick or injured, a practice among conventional producers that has been widely criticized for its health risks.

At the Community Mercantile, King said some consumers are bypassing beef altogether. He said poultry and pork sales also have made strides since the announcement.

“Chicken is flying off the shelves, a lot of people are finding other options other than beef,” King said.

Despite the increase in organic, other Lawrence grocery stores haven’t seen a decline in sales of non-organic beef. Shawn Brown, store manager at Hy-Vee Food and Drug Store, 4000 W. Sixth St., said beef sales were pretty much unchanged since late December.

“We haven’t seen any sign of a widespread scare or anything like that,” said Brown, who speculated consumers hadn’t become concerned because only one cow has been found to have the disease — and the cow was later found to have come from Canada.

Brown said Hy-Vee also stocked a line of organic beef but said sales had not spiked for it — or chicken or pork.

“I would say it is just consistent sales like always,” Brown said. “I don’t think there has been a change in buying habits one way or the other.”

Business editor Chad Lawhorn contributed information to this report.