African cattle have many traits that allow them to withstand harsh climatic conditions and diseases hence making them an ideal investment for farmers, according to a new study.
The study, conducted by the International Livestock Research Institute (ILRI) and other partners has unearthed a new set of detailed genetic markers and information that are associated with valuable traits such as heat and drought tolerance, the ability to control inflammation and tick infestations, and resistance to devastating livestock diseases like trypanosomiasis.
Researchers deployed advanced tools to retrace 1,000 years of African pastoralist cattle breeding, identifying traits to help cattle survive blistering heat, drought and advancing diseases.
Their findings, which will appear in next month's issue of Nature Genetics, emerged from a collaborative effort to sequence the genomes of 172 indigenous cattle by scientists at ILRI, Seoul National University, Rural Development Agency (South Korea), University of Khartoum, The Centre of Tropical Livestock Genetics and Health (Scotland), Uppsala University (Sweden) and the University of Nottingham (UK).
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ILRI is a Consultative Group on International Agricultural Research Centre co-hosted by Kenya and Ethiopia, and has 14 other offices across Africa and Asia.
The team 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.
Mosaic of traits
"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 ILRI principal scientist Olivier Hanotte.
Prof 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.
The researchers discovered what co-author Steve Kemp, leader of ILRI’s LiveGene programme, described as an “evolutionary jolt” that occurred 750 to 1,050 years ago. They studied the arrival of Asian cattle breeds in East Africa carrying genetic traits that would make cattle production possible in diverse and demanding African environments.
Their work yielded evidence that indigenous pastoralist herders began breeding the Asian cattle, known as Zebu, with local breeds of cattle known as Taurine. The study shows 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.
"Livestock, especially cattle, can 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,” said co-author Ally Okeyo Mwai, a principal scientist at ILRI who leads its African Dairy Genetic Gains programme.
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.
The African continent is home to an extraordinary array of indigenous cattle; from the small Lobi to the large-bodied Ethiopian Boran, the humpless N’Dama to the humped Red Fulani, the favoured white of the Kamba to the deep, dark red of the Ankole.
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. They provide nutrition, manure and draught power, and are often used as bridewealth.
They also provide manure for crops, and some cattle breeds can survive in conditions that can’t support food crops, offering farmers a potential adaptation strategy for coping with climate change.
"We are fortunate that pastoralists are such skilled breeders. They left a valuable roadmap for efforts underway at ILRI and elsewhere to balance livestock productivity in Africa with resilience and sustainability,” Hanotte said.
Kemp said the researchers studied the genomes of indigenous cattle and concluded that breeding for environmental adaptation has been the key to successful livestock production. "That has to be factored in our future efforts to develop more productive, more sustainable animals. If the goal is pure productivity, you are doomed to fail."
Jimmy Smith, the ILRI director general said it is 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."
With African farmers and pastoralists facing a triple threat of climate change, locusts and Covid-19, the researchers said their findings could be critical for securing the well-being of millions of households that depend on cattle for income, nutrition, fertiliser and tractor power. [The writer is a 2019/2020 Bertha Fellow]