One of Japan's most prized stud bulls has been infected with foot-and-mouth disease, the government said Saturday, as the country's first outbreak in a decade continues to devastate livestock.
The discovery was a blow to the southern prefecture of Miyazaki, which evacuated the region's six top seed bulls, including the affected animal, to a special facility to keep them away from the disease, which has hit more than 100 farms in the area.
The highly contagious virus has brought to a halt all Japanese beef and pork exports for the past month and crippled the premium beef industry in Miyazaki.
The six bulls are the only remaining breeding animals for the highly sought-after "Miyazaki beef", as the foot-and-mouth outbreak which began last month has forced the cull of 49 other seed bulls in the prefecture.
Between them, the six bulls accounted for some 90 percent of artificial breeding in the prefecture, Kyodo News said.
"The affected bull shall be immediately slaughtered," the farm ministry said in a statement.
The other five animals have so far tested negative for the disease, and "will remain under observation," the statement said.
Usually, all bulls and pigs kept with infected animals are culled, but officials have decided to keep the five remaining seed bulls under observation for a week in an effort to preserve the premium Miyazaki beef strain, Kyodo said.
The news came as officials prepared to slaughter some 205,000 animals in Miyazaki -- 50,000 cows and 155,000 pigs -- as the highly contagious disease spreads rapidly in the region.
The six prized stud bulls were removed from their regular farm near the areas hit by the disease and were assigned individual care managers and kept in separate stalls in a bid to stop them contracting the disease.
Japan's famed "Wagyu" beef is sought-after worldwide for its intense marbling with mostly unsaturated fat, and the variety from Miyazaki typically wholesales for up to 320 dollars a kilogram in Japan.
The latest foot-and-mouth outbreak, Japan's first since 2000, was detected on April 20 and spread quickly in Miyazaki, on the southwestern island of Kyushu.
The health threat prompted Prime Minister Yukio Hatoyama to pledge more than a billion dollars to help farmers who have to slaughter their livestock.
Foot-and-mouth disease affects cloven-hoofed animals, also including sheep, goats and deer. It is rarely transmitted to humans but spreads easily between animals, causing them pain and often killing their young.