Britain's first beef exports to the United States in more than 20 years left Northern Ireland on Wednesday, six months after Washington lifted a ban, the government said.
"This is great news for our food and farming industry, who have estimated it will bring a £66 million ($85 million, 72 million euros) boost to beef producers over the next five years alone," Environment Secretary George Eustice said.
Washington imposed restrictions on all EU beef exports in 1998 due to concerns about mad cow disease but has gradually eased them as it tries to negotiate a free trade deal with Brussels.
It has permitted Irish beef imports since 2015 and granted the Netherlands approval to renew its exports the following year.
Britain, which left the European Union on January 31 after the 2016 Brexit vote, received permission to restart its transatlantic beef shipments in March.
British herds were badly hit by mad cow disease -- officially known as bovine spongiform encephalopathy (BSE) -- in the late 1980s and 1990s.
More than four million cows were slaughtered, then burned on huge pyres across the countryside, in an effort to contain the spread.
Eating infected beef can cause the degenerative brain condition variant Creutzfeld-Jakob Disease (vCJD) in humans. In 2000, 24 people died in Britain from vCJD.
Britain is aiming to strike a free trade deal with the United States as the country tries to take advantage of life outside the EU from 2021.
Although the country formally left the bloc earlier this year, it is still abiding by EU rules in a standstill transition period until December 31.
International Trade Secretary Liz Truss said the resumption of beef exports to the US "could be just the tip of the iceberg".
"The free trade deal we are negotiating with the US will create a host of export opportunities for British agriculture," she added.
"We are seeking an ambitious and high standards agreement that benefits farmers and delivers for consumers."