SCIENTISTS have revealed of a new set of detailed genetic traits in African cattle that provide heat and drought tolerance, control inflammation and tick infestations, and resistance to devastating livestock diseases including trypanosomiasis.
The findings, published in the October issue of Nature Genetics, emerged from a global, collaborative effort spearheaded by the International Livestock Research Institute to sequence the genomes of 172 indigenous African cattle.
The scientists wanted to learn how - after spending thousands of years confined to a shifting patchwork of sub-regions in Africa - cattle rapidly evolved during the last millennia with traits that allowed them to thrive across the continent.
Olivier Hanotte, who led the work at ILRI and is a professor of genetics at the University of Nottingham, said the new information could be used to breed a new generation of African cattle. In particular, cattle that had some of the qualities of European and American livestock - which produce more milk and meat per animal - but with the rich mosaic of traits that make African cattle more resilient and sustainable.
Professor Hanotte and his colleagues engaged in a sort of "genomic time travel" that, for the first time, allowed scientists to retrace the genetic journey that has made African cattle so adaptable.
They discovered what co-author Steve Kemp, leader of ILRI's LiveGene program, described as an "evolutionary jolt" that occurred 750 to 1050 years ago: the arrival of Asian cattle breeds in East Africa carrying genetic traits that would make cattle production possible in diverse and demanding African environments.
The genome sequencing work yielded evidence that indigenous pastoralist herders began breeding the Asian cattle, known as Zebu, with local breeds of cattle known as Taurine.
In particular, the Zebu offered traits that would allow cattle to survive in hot, dry climates typical in the Horn of Africa. But by crossing the two, the new animals that emerged also retained the capacity of the Taurines to endure humid climates where vector-borne diseases like trypanosomiasis are common.
Professor Shaun Coffey, the director of capacity building at the Crawford Fund and former chief of CSIRO Division of Livestock Industries, said the ILRI research had potential impacts far beyond Africa.
"Australia has benefited from African genetics through initiative such as the introduction of Boran and Tuli cattle by CSIRO in the 1990s and improvements in heat and disease resistance in the northern herds," Professor Coffey said.
"The new gene markers for traits, such as heat and drought tolerance will be of enormous value in future breeding programs."
Author Ally Okeyo Mwai, a principal scientist at ILRI who leads its African Dairy Genetic Gains program, said livestock - especially cattle - could be controversial, but without them, millions of people in Africa would have been forced to hunt wildlife for protein.
"That would have been devastating for the African environment and its incredible diversity of wildlife," Dr Okeyo Mwai said.
It is now important to use the full range of natural genetic endowments that have made African cattle so resilient to sustainably meet Africa's surging demand for milk and meat, while minimising negative impacts of increased livestock production.
For many households in Africa, and especially the poorest, livestock in general and cattle in particular continue to be a family's most valuable asset.
They provide a critical source of protein and micronutrients alongside income to pay for things like school fees. They also provide manure for crops, and some African cattle breeds can survive in conditions that can't support food crops, offering farmers a potential adaptation strategy for coping with climate change.
"We're fortunate that pastoralists are such skilled breeders," Professor Hanotte said.
"They left a valuable roadmap for efforts underway at ILRI and elsewhere to balance livestock productivity in Africa with resilience and sustainability."
Dr Kemp said you can see from studying the genomes of Indigenous cattle that breeding for environmental adaptation has been the key to successful livestock production in Africa," Kemp said.
"And that has to be the factored in our future efforts to develop more productive, more sustainable animals. If the goal is pure productivity, you're doomed to fail."
ILRI director general Jimmy Smith said it was important to understand that livestock breeding has long played a vital role in sustaining the health and wealth of African communities.
"The focus on breeding for resilience that guided past efforts provides a touchstone for future work to chart a sustainable path for livestock production in sub-Saharan Africa."
Scientists carrying out the research were from the Addis Ababa and Nairobi-based International Livestock Research Institute, Seoul National University, Korea; Rural Development Agency, Korea; University of Khartoum, Sudan; The Centre of Tropical Livestock Genetics and Health, Scotland; Uppsala University, Sweden; and the University of Nottingham, UK.
