NAIROBI, Kenya, July 21 (UPI) -- A rapid loss of genetic diversity in native African livestock could create a threat to the continent's food supply, experts say.

The genetic diversity that maintains drought- and disease-resistant animals providing food and income to 70 percent of rural Africans is being lost at an alarming rate, a release by the International Livestock Research Institute said Tuesday.

Efforts must be made to identify and preserve the unique traits of the continent's rich array of cattle, sheep, goats and pigs developed over several millennia but now under siege, the ILRI said.

The loss of livestock diversity in Africa is part of a global "livestock meltdown," the institute said.

According to the U.N. Food and Agriculture Organization, some 20 percent of the world's 7,616 livestock breeds are now viewed as at risk.

"Africa's livestock are among the most resilient in the world yet we are seeing the genetic diversity of many breeds being either diluted or lost entirely," Abdou Fall, leader of ILRI's livestock diversity project for West Africa, said.

Cross-breeding with "exotic" breeds imported from Europe, Asia and the Americas is a major problem, ILRI officials said.

"What we see too often is an effort to improve livestock productivity on African farms by supplanting indigenous breeds with imported animals that over the long term will prove a poor match for local conditions and require a level of attention that is simply too costly for most smallholder farmers," Carlos Sere, ILRI's director general, said