Animal diseases cost cash-strapped African farmers about $300 billion a year in lost income and veterinary bills. Now scientists are proactively breeding livestock with defenses against these pests before they strike.

Scientists from the Consultative Group on International Agricultural Research (CGIAR) consortium are setting up a “preemptive breeding” program to develop livestock with resistance to potential widespread outbreaks of currently localized diseases to help reduce some of the losses that would occur.

Most of the world's 38 billion livestock are kept in Africa where they face threats from diseases, reduced grazing land and a lack of vaccines. Livestock in Europe or the U.S., by contrast, are rarely lacking in food and medicine, says Okeyo Mwai, a livestock geneticist at the International Livestock Research Institute (ILRI) in Kenya. “Most of the problems are in Africa where the costs of treating diseases are huge. As climate change makes diseases spread to new areas, that figure will rise astronomically,” Mwai says.

CGIAR scientists presented their preemptive breeding strategy and new evidence of threats from climate change to the science advisory body of the United Nations Framework Convention on Climate Change on June 4.

Current breeding strategies are inadequate because they are too slow to respond to disease outbreaks and climate challenges, the CGIAR researchers told the UNFCCC science advisory body. “The level of losses can be reduced if we proactively breed animals that are resistant and don't require direct treatment,” Mwai says.

As part of their proactive breeding program, the CGIAR researchers are drawing up a map of African livestock that are resilient to pests and environmental stresses such as heat. They use predictions of climatic changes and disease threats to focus their search for these desirable traits. When threats arise in new areas, the scientists will be able to easily locate resistant animals and then quickly breed them with varieties that are local to the areas at risk. “We need to be proactive. If those future cases arise, we will know where to go to get the livestock,” Mwai says.

For example, the Maasai tribe in Kenya have over many years bred sheep that are resistant to a deadly parasitic worm. The scientists are now working with these farmers to help introduce this breed to new areas that are suffering with high levels of the parasite.

Resistant livestock should not be introduced into areas that are disease-free because they still carry the pest and could cause an outbreak, Mwai says. He suggests that resistant breeds be brought in when predictions indicate the imminent arrival of an infection.

The scientists also hope to use new high-tech tools to develop tougher livestock. They are planning a research program that will use genome editing to take genetic material from resistant breeds and paste it into susceptible ones. This technology will allow a much more “precise” approach to creating animals with desirable traits.

In contrast, traditional breeding methods “mix and match” genes by mating individuals “in the hope” of producing individuals beneficial traits, Mwai says. But sexual reproduction offers no guarantees that offspring will exhibit the desired traits of the parents. “We need precision, not shotgun breeding,” he says.

The CGIAR team hopes to use genome editing to breed new populations of cattle that are resistant to trypanosomiasis. The scientists are studying N'Dama cattle from west Africa, which have a natural resistance to the disease, and have located the genetic material responsible for the breed’s protection. Next they will put that material into populations with other desirable traits such as increased milk and meat production.

Toughening agriculture for a worsening climate
Preventative breeding is becoming increasingly urgent as livestock diseases continue to march across Africa, the CGIAR researchers say. New research they presented to the science advisory body shows that 44 percent of all major livestock diseases they studied are increasing in prevalence continent-wide. The researchers also found that farmers will lose up to half of suitable grazing land over the next century, placing livestock under further pressure from already limited feed supplies.

The CGIAR scientists also want to use breeding to develop tougher crops. “We find that for many staple crops in the regions, climatically suitable areas are projected to decrease in countries that are most dependent on them,” says Julian Ramirez-Villegas, who studies climate impacts on agriculture at the University of Leeds in England.

The International Center for Tropical Agriculture (CIAT) in Colombia has already begun work to develop heat tolerant beans that it hopes to roll out to areas that might need them now and in future.

Focusing agricultural research efforts on building resilience against future climatic and disease threats will help vulnerable farmers produce food even under the most difficult conditions, says Ramirez-Villegas, formerly of the CIAT. “Pushing the biophysical limits of the crop, we would be able to carry on cropping beans everywhere where beans are currently grown even under the most pessimistic climate scenarios by mid-century,” he says. By the end of the century, only in the high-end warming scenarios heat-adapted beans would be affected.