Researchers with the International Livestock Research Institute (ILRI) and other institutions have reported a new set of detailed genetic markers and information on African cattle associated with traits such as heat and drought tolerance, the capacity to control inflammation and tick infestations and resistance to devastating livestock diseases like trypanosomiasis.
The findings, published in the October issue of Nature Genetics, emerged from a collaborative effort to sequence the genomes of 172 indigenous cattle by scientists at the Ethiopia- and Kenya-based ILRI, Seoul National University and the Rural Development Agency in South Korea, University of Khartoum in Sudan, The Centre of Tropical Livestock Genetics & Health (CTLGH) in Scotland, the Swedish University of Agricultural Sciences in Sweden and the University of Nottingham in the U.K.
The researchers 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, ILRI said in an announcement.
“We believe these insights can be used to breed a new generation of African cattle that have 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,” said Olivier Hanotte, principal scientist at ILRI, professor of genetics at the University of Nottingham and program leader at CTLGH.
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, ILRI said. They discovered what co-author Steve Kemp, head of ILRI’s LiveGene program and deputy director of CTLGH, described as an “evolutionary jolt” that occurred 750-1,050 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, Zebu cattle offered traits that would allow them to survive in the hot, dry climates typical in the Horn of Africa. However, by crossing the two cattle types, the new animals that emerged also retained the capacity of the Taurines to endure humid climates where vector-borne diseases like trypanosomiasis are common, ILRI reported.
“Livestock, especially cattle, can be controversial, but without them, millions of people in Africa would have been forced to hunt wildlife for protein,” said co-author Ally Okeyo Mwai, a principal scientist at ILRI who leads its African Dairy Genetic Gains program. “That would have been devastating for the African environment and its incredible diversity of wildlife.”
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 minimizing the negative impacts of increased livestock production, ILRI said.
For many households in Africa, livestock — particularly cattle — continue to be a family’s most valuable asset, ILRI said. The animals 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 cannot support food crops, offering farmers a potential adaptation strategy for coping with climate change, according to the announcement.
“We’re fortunate that pastoralists are such skilled breeders,” Hanotte said. “They left a valuable roadmap for efforts underway at ILRI and elsewhere to balance livestock productivity in Africa with resilience and sustainability.”
“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. “That has to be factored in our future efforts to develop more productive, more sustainable animals. If the goal is pure productivity, you’re doomed to fail.”
ILRI is a nonprofit institution helping people in low- and middle-income countries improve their lives, livelihoods and lands through the animals that remain the backbone of small-scale agriculture and enterprise across the developing world.