OMAHA, Nebraska - Now that Japan has lifted its ban on U.S. beef, American beef producers are eager to resume trade there, but analysts say restoring sales to pre-ban levels and regaining the trust of Japanese consumers will be a slow process.

"The Japanese consumer likely has a lot of questions about the safety of the U.S. product," said Darrell Mark, an agricultural economist with the University of Nebraska's Institute of Agriculture and Natural Resources.

Fears of mad cow disease prompted Japan and other countries to ban U.S. beef in 2003, but that ban was lifted in December.

Safety concerns prompted a new ban in January when Japanese inspectors checking a veal shipment found banned parts believed to be at risk for the illness. The latest ban was lifted Thursday after Japanese representatives toured U.S. facilities to ensure they met safety guidelines.

Mad cow disease _ formally known as bovine spongiform encephalopathy, or BSE _ is a degenerative nerve disease in cattle. In humans, eating meat contaminated with BSE is linked to variant Creutzfeldt-Jakob Disease, a rare and deadly nerve disease.

U.S. officials and industry representatives maintain that there is no reason to question the safety of American beef, and groups like the Denver-based U.S. Meat Export Federation have already started trying to convince the Japanese.

The federation has tried to keep Japanese customers informed about new procedures and safety precautions, federation spokesman Lynn Heinze said. There will also be a campaign to let Japanese beef importers and consumers know that American beef producers care about safety of their product, he said.

The beef trade with Japan is important to the industry because it was the top export market for U.S. beef. About $1.4 billion of U.S. beef was sold in Japan in 2003.

Beef producers from Australia, New Zealand and South America have moved into the Japanese market since 2003, but Heinze said less beef is being eaten in Japan today than before the scare about mad cow disease.

Before the ban, beef accounted for about 5 percent of the protein consumed in Japan, he said. Now beef accounts for only about 3.5 percent of the protein the Japanese eat.

Opinion polls the federation has conducted in Japan show that less than 10 percent of consumers say they're confident the U.S. Department of Agriculture's inspections will ensure beef is safe. At the height of U.S. beef sales there, only about 20 percent of Japanese consumers expressed confidence in the inspections, he said.

The export federation expects that it will take three to four years to return to normal levels of trade in Japan, Heinze said.

Pete McClymont, president of the Nebraska Cattlemen, said he's looking forward to full trade with Japan. Before the 2003 ban, Nebraska sold about $300 million of beef products annually to Japan.

"We will be more pleased after we know the first load has been received in Japan and after multiple shipments prove Japan is sincere about being a fair trading partner again," the feedlot owner said.

Mark, the agricultural economist, wasn't sure how long it would take to restore the beef trade with Japan to 2003 levels. These days, exports account for only about 5 percent of all U.S. beef sales, which is half of the pre-ban figure, Mark said.

"It's going to take months or years until we get back to that point," Mark said.