Updated

As U.S. beef producers readied their first shipments to Japan in two years, the Bush administration on Monday lifted its ban on expensive Japanese beef.

The discovery of mad cow disease in both nations had prompted the trade restrictions.

Japan's action has greater financial significance. The country's market, the most lucrative for U.S. beef, was worth $1.4 billion before mad cow disease was discovered in the United States in December 2003.

The U.S. appetite for Japanese beef, primarily expensive Kobe beef, is more of a niche market worth an estimated $808,000 annually.

The first American beef shipment is planned for next weekend, the National Cattlemen's Beef Association said Monday. The group is rounding up steaks and other products from meat-processing plants for a shipment that will leave Denver on Saturday.

"We're confident consumers and the Japanese government will find it goes above and beyond their expectations," said Illinois cattle rancher Jamie Willrett, chairman of NCBA's international markets committee.

Agriculture Secretary Mike Johanns said Japanese inspectors will be visiting plants to certify them in the coming days.

"We know of many plants across the United States who have been anticipating this day," Johanns said from Monday Hong Kong, where he is participating in global trade talks. "They are prepared to deal with the export verification requirements, and so I'm optimistic. I think the industry will adjust very quickly."

In an interview Sunday night with The Associated Press, Johanns said, "I think we'll see plants that are given the green light yet this week."

U.S. officials called on other Asian countries, including Taiwan, South Korea and Singapore, to follow Japan's lead.

"Now 70 countries are open to U.S. beef," said U.S. Trade Representative Rob Portman, who was with Johanns in Hong Kong. "I encourage other trading partners to move forward expeditiously."

Japan will allow beef from animals under 20 months of age, which opens the market to 94 percent of U.S. beef, Johanns said. The age restriction is because infection from mad cow disease is believed to spread with age.

Japan and dozens of other countries banned U.S. beef after mad cow disease was confirmed in a cow in Washington state that had been imported from Canada. U.S. officials in June confirmed a second case in a Texas-born cow.

Since 2001, the U.S. has imposed a ban on beef from Japan, which has found 21 cases of mad cow disease. The Agriculture Department said Monday morning it will lift the ban to allow whole cuts of boneless beef from Japan under certain conditions. That allows expensive Japanese Kobe beef, prized for its intense marbling of fat, to be sold in the U.S.

"We are ready for that market to open," Johanns said during a press conference in Hong Kong at the World Trade Organization meeting.

Mad cow disease is the common name for bovine spongiform encephalopathy, or BSE, a degenerative nerve disease. In people, eating contaminated meat products is linked to a rare but fatal disease called variant Creutzfeldt Jakob disease. More than 150 people have died of the disease, most of them in the United Kingdom, where there was an outbreak in the 1980s and 1990s.