Farm scientists have warned that hardy breeds of livestock vital for world food supplies were dying out across developing countries, especially in Africa.

They called for the creation of regional gene banks to save them.

In a report to a conference in the Swiss town of Interlaken, the experts said tough and adaptable animals were being ousted by others from richer countries that were more productive in the short-term but posed a longer-term risk for farm output.

"There is a livestock meltdown under way across Africa, Asia and Latin America. Valuable breeds are disappearing at an alarming rate," Carlos Sere of the International Livestock Research Institute (ILRI) told the week-long gathering.

"In many cases we will not even know the true value of an existing breed until it has already gone," declared Sere, director-general of the Nairobi-based body which focuses on livestock research for development.

The report, from the United Nations Food and Agriculture Organisation (FAO), found that smallholders in poorer nations were abandoning their traditional animals in favour of higher-yield stock imported from Europe and the United States.

This growing reliance on a handful of farm animal species is causing the loss on average of one livestock breed every month in developing economies, the report said.

Holstein-Friesian cows with high milk yields, fast egg-laying White Leghorn chickens and quick-growing Large White pigs -- all from the industrialised and more temperate countries of the North -- were pushing out native species in the South.

In northern Vietnam, local breeds made up 72 percent of the sow pig population in 1994 but eight years later the proportion had dropped to 26 percent. Of the 15 local pig breeds, 10 now faced possible extinction, according to the report.

ILRI's Sere told the conference -- attended by 300 policy-makers, scientists, breeders and farmers from around the globe -- that the highly-bred varieties from the North offered short-term benefits with high volumes of meat, milk or eggs.

But over the longer term, they posed a serious risk because many could not cope with unpredictable environmental change or outbreaks of indigenous disease when introduced to the more demanding conditions of the South.

Many experts were predicting that Uganda's indigenous Ankole cattle, famous for their graceful and gigantic horns, could be extinct within 20 years because they are being rapidly supplanted by Holstein-Friesians.

However, during a recent drought, farmers who had kept their tough Ankole were able to walk them long distances to water sources while those who had switched to the imported breeds lost their entire herds, Sere said.

Across the world, according to the FAO, one billion people -- nearly one sixth of the global population -- are involved to some degree in animal farming, and 70 percent of the rural poor depend on livestock for much of their income.

"For the foreseeable future," Sere told the gathering -- the First International Technical Conference on Animal Genetic Resources -- "farm animals will continue to create means for hundreds of millions of people to escape absolute poverty."

He noted that gene banks had been set up in Europe and the United States as well as in China, India and parts of Latin America. But their absence in Africa was a serious problem because it was a region with the richest remaining diversity.

Another way to tackle the issue, Sere said, was the application through international cooperation of "landscape genomics" -- mapping techniques which help predict which breeds are best suited to different environments around the globe.  -Reuters