The Ankole cattle of Uganda boast long, curved horns. The breed has thrived in this eastern African country for millennia thanks to its ability to subsist on poor forage and limited water [see video here]. But facing growing consumer demand for milk, these native cattle are increasingly being replaced by European Holstein-Friesian cows—known for their distinctive black patches and their ability to produce prodigious quantities of milk—and the U.N. Food and Agriculture Organization (FAO) warns that Ankole could become extinct within 20 years.

But during a recent drought, herds of such European imports were wiped out, while farmers who still relied upon Ankole found their cattle were sturdy enough to walk the extra mile to water. Such hardiness in the face of locally tough conditions is a hallmark of the regional versions of various livestock breeds, such as worm-resistant Red Maasai sheep [see video here] and Sheko cattle with their immunity to sleeping sickness [see video here]. Given the threats posed by climate change and evolving disease, researchers say that holding on to that diversity may prove key to ensuring steady supplies of fresh milk and other animal products.

Agricultural economist Carlos Sere, director general of the International Livestock Research Institute (ILRI), and his colleagues recently completed a global inventory of the 7,000 existing? livestock breeds for the FAO. Of these, 40—such as the Holstein-Friesian cow, White Leghorn chicken, and Large White pig—form the basis of industrial agriculture in the developed world; in fact, 90 percent of cattle in the industrialized world come from just six breeds.

Thanks to the ability of those 40 breeds to produce massive amounts of milk, eggs and meet, there has been a worldwide explosion in their use to meet the needs of both farming communities and consumers in the developed and, increasingly, developing world For example, Vietnam boasted local breeds for 72 percent of its pigs in 1994 but by 2002 saw them drop to 26 percent of pigs, replaced in large part by the faster-growing Large White pig.

"In pursuit of quick wins to increase productivity to meet demand in developing countries, a strategy adopted by these nations over the last half century has been importation of specialized, high-producing breeds," Sere says. This happened "in the absence of adequate information on the robustness, hardiness [and] appropriateness of native breeds versus imports."

As a result, 696 breeds have become extinct since 1900 and some 1,487 breeds are at risk, including 579 in imminent danger of disappearing. This will cause a loss of genetic diversity that might enable resistance to future disease outbreak (such as avian flu) or adverse environmental conditions. "The unpredictability of the nature and scope of these changes,'' Sere argues, "demand that these genetic options be safeguarded."

Lost traits would be difficult to re-create, he says, because modern livestock lack living wild relatives—a reserve of potentially useful genes that has saved agricultural crops in the past. "We do not even know the traits we will need in the future and which of the present breeds possess the requisite genes," he says.

One billion people, largely in the developing world, raise livestock and 70 percent of those living in extreme poverty rely on this practice to survive. And the wealthier people are, the greater their appetite for meat, eggs and milk grows. "We expect that the developing world will double their consumption of animal products in the next 20 years," Sere notes. "This has to happen from basically the same or shrinking resources," given the environmental problems associated with intensive animal husbandry.

As a result of these findings—and looming demand—the ILRI is urging action to preserve native breeds. Among its recommendations: encourage local farmers to maintain local types of livestock; share breeds across borders (particularly when breeds are likely to be suited to specific regions due to certain adaptive traits, such as a need for less water); and establish a gene bank—similar to the regional seed banks that preserve crop diversity—to maintain this genetic heritage.

The greatest part of genetic heritage—and the largest numbers of livestock in general—are concentrated in the developing world. While some gene banks exist in developed regions, Sere says that more—and broader—banks will also be needed in the rest of the world. "It is not good enough for southern countries to depend on the North to be custodians of their livestock genetic material," he says. "The fastest and most effective route through which the North can make a contribution [to diversity] is to assist developing nations to establish capacity to save endangered breeds in these countries."