Tropical grasses and other forages can boost livestock sustainability – and not just in the tropics

Incipient research on a vast collection of tropical forages – grasses, shrubs, legumes and trees – shows that changing livestock diets can significantly reduce greenhouse gas emissions. Founded on a vast, decades-old collection of carefully preserved seeds, rapid technological advances allow scientists to unlock transformative ways to reduce livestock farming’s outsized environmental footprint.

A team of scientists lead Andy the short-haired sheep into an airtight chamber and serve him a precise portion of Guinea grass. Andy will spend the next 24 hours in the high-tech enclosure while the researchers measure how much methane Andy releases while digesting the Megathyrsus maximus. The little-used forage is one of dozens of palatable, nutritious and easily digestible pasture grasses researchers are analyzing at the Alliance of Bioversity International and CIAT in Colombia. They expect the research results will uncover more methane-mitigating grasses that farmers can use to change livestock diets and significantly reduce the industry’s planet-heating emissions.

Andy and his charismatic ovine buddies – who spend most of their time roaming silvopastoral areas across the Alliance’s sprawling 500-hectare campus – may be the newest darlings of the forages lab, but they are just one part of ongoing research aimed at making livestock systems more sustainable.

Recent Alliance research, using less sophisticated enclosures, found diet changes reduce methane emissions from grazing livestock by up to 15%. Researchers found improved pasture grasses that decrease nitrous oxide (N₂O) emissions from livestock urine by 10 times compared to conventional grasses. Scientists found improved grasses with meter-deep roots – more than three times deeper than many conventional grasses – with the potential to significantly increase soil carbon sequestration, restore degraded land, and mitigate climate shocks like drought and deluges.

Powered by rapid advances in genotyping, phenotyping and artificial intelligence – and the Alliance’s access to a vast repository of understudied tropical forages – the work is set to accelerate. With the livestock industry under increased scrutiny for its outsized contribution to climate change, the timing is perfect. Crucially, the research taps into the livestock industry’s edge over others in the climate fight.

“Agriculture systems, livestock in particular, have an advantage over other sectors in taking meaningful climate change action,” said Jacobo Arango, an environmental biologist and the Alliance’s forage team leader. “Better livestock management can both reduce greenhouse gas emissions and capture them. Other major emitters like transportation and energy can only reduce emissions.”

The advantage matters. Rapidly reducing GHG emissions is urgent to curb climate change but it is not enough. Carbon capture is essential to keeping global warming below 2 degrees Celsius, scientists concluded in the most recent major report by the Intergovernmental Panel on Climate Change (IPCC).

Agriculture is the world’s leading source of human-caused methane emissions, which have driven about 26% of warming since the Industrial Revolution. Livestock is responsible for about 12-19% of total methane emissions. N₂O, the world’s “forgotten greenhouse gas,” is responsible for about 10% of climate warming; about 40% comes of which from livestock. Livestock, especially in tropical regions, drives deforestation, with devastating impacts on carbon storage, biodiversity, ecosystems, and the communities that depend on them.

There are no simple solutions, but increasing the use of nature-friendly forages, such as improved grasses and legumes in tropical livestock systems and industrial feed production, could significantly cut GHG emissions.

Some climate advocates call for people to reduce, or even end, the consumption of red meat and animal-sourced food. But there is a strong – and more realistically attainable – argument for transforming livestock systems to address their climate impacts.

While decreased meat consumption in rich countries should be a public health priority, many developing nations increasingly consume meat. In poor countries, more meat on the table can efficiently fix pervasive nutrition deficiencies, particularly in Africa, where one in five people face hunger and suffer from related, often devastating health consequences.

“Scaling up sustainable livestock systems is critical to the health of the planet and millions of people,” explained Arango, a lead author on an IPCC report on mitigating climate change. “And if you multiply the potential for GHG mitigation across millions of hectares of degraded pastureland, we can make major contributions to carbon storage in soils, and significantly reduce the planet-heating effects of methane and nitrous oxide.”

The Alliance’s latest greenhouse gas mitigation (GHG) research, which has implications for increased livestock sustainability beyond the tropics, is still incipient. Yet it builds on decades of conservation and research by the Alliance and other CGIAR centers. Scientists are confident their work will lead to more cost-effective, sustainable feed options for grazing livestock and intensive systems.

SEEKING METHANE MITIGATORS
A few hundred meters from the methane lab is the Future Seeds, which houses 22,657 accessions of tropical forages collected from 75 countries. The accessions are viable collections of seeds from 690 species of grasses, legumes, shrubs and trees eaten by livestock. The methane lab’s experimental forages come from the repository, which CGIAR scientists collected during the 1970s and 1980s, a time of rampant ecosystem destruction from urbanization and loss of traditional crops and forages for industrial replacements. (The collections were housed in a converted slaughterhouse until Future Seeds opened in 2022.)

“Their mission was to conserve as much as possible before it disappeared,” said Juan José Gonzalez, who manages the Alliance’s forages collection. Future Seeds, part of CGIAR’s global network of gene banks, also contains the world’s largest collections of common beans and cassava accessions; almost 38,000 and 6,000, respectively.

Since most of the collection was formed well before the scientists sequenced the first crop genome – Ozyra (rice), in 2006 – (and when the reality of climate change seemed a distant threat) the seed collectors could probably only imagine the 21^st-century value of what they saved. Rapid advances in genomic sequencing, artificial intelligence and data analysis are unlocking the forages collection’s potential for addressing climate change, nutrition, food security and productivity.

And scientists are only getting started. Only 5% of the forage accessions are fully sequenced.

“The vast forage collection in the gene bank gave us the impetus for the methane project,” said Juan José Gonazlez, who manages the collection. “We have many understudied, underutilized grasses that we can likely use to mitigate emissions from livestock systems. We’re now preparing to test forages for several other stressors facing livestock systems, including heatwaves, low soil fertility, high salinity, flooding and freezing temperatures.”

Before grasses are sent to Andy’s feeding trough, scientists at Future Seeds screen them for desirable traits. These include high concentrations of tannins and other chemicals that reduce methane emissions from ruminant digestion. They also look at resistance to trampling, nutritional value and palatability, which tannins can reduce. “They key is finding the right balance,” Gonzalez said. Scientists also use a massive database built over decades of CGIAR research, Tropical Forages, to find relevant data.

The forage collection’s potential extends beyond reducing GHG emissions. Once sequenced, scientists can look for the genes, gene sequences, metabolomics (the study of the process of metabolization) and molecular markers responsible for the desired traits. This opens the door to allele mining, which researchers around the world can use to breed improved crops at the pace demanded by climate change.

“We’re in stage of pure discovery,” Gonzalez explained. “These are plants that no one had previously studied in this way; no one said ‘let’s invest in making metabolic profiles of these plants.’ But that’s exactly what we’re doing.”

Gonzalez envisions a future where climate-friendly gene bank material is used at scale in grazing livestock systems and by industrial feed producers. The future may already be arriving. Last year, Gonzalez and colleagues published research in PLOS One on how combining traditional and high-tech tools to study crop traits can speed up gene bank research and crop breeding.

“When I speak with major feed-makers in Colombia, I ask them why they import costly soy and maize to make feed,” Gonzalez said. “You can instead forge alliances with local producers who can cultivate the forages we have, in the right combinations that you need, and make nutritious pellets at a fraction of the cost in just a few months.”

Gonzalez said the gene bank’s forages could significantly reduce grain production costs and negative environmental impacts. Some varieties only need initial watering after planting, then grow vigorously with minimal intervention. They require little machinery, fertilizer, or pest control, rapidly producing valuable biomass. It’s a win for both farmers and the environment.

As the planet warms and desertification spreads north, the gene bank’s collection’s relevance for outside the tropics extends beyond allele mining. One successful strategy for restoring degraded land also wreaked by desertification uses a stepwise approach that begins with planting small, robust plants (many of which are in Future Seeds) that can restore soil nutrients and retain moisture. Planting suitable trees follows. Gonzalez points to accomplished restoration projects in Africa that employ this strategy. If adopted by restorationists in places dealing with desertification like Spain or the Southwestern United States, it could turn the development paradigm on its head by transferring knowledge from the south to the north – and further underscore the global importance of foreign climate aid.

Additionally, plants no longer feasible for restoration in the Global North can be replaced by tropical plants already adapted to harsh weather.

“The climate is changing in the global north, and if the species we have there are not adapting, why don’t we try including some of the forages we have here to test their viability for restoring landscapes, slowing desertification and improving degraded soils?” Gonzalez expressed.

WHAT’S IN THE WAY OF WIDESPREAD UPTAKE?
When coupled with nature-positive agricultural practices like silvopastoral farming, improved forages have proven to be an integral part of improving the sustainability and productivity of livestock systems. But why is widespread uptake so slow?

Urgency alone doesn’t seem to be enough of an incentive.

“Upgrading livestock production toward greater sustainability is mandatory to achieve our climate goals,” said Augusto Castro, an Alliance researcher specializing in low-emission food systems and post-conflict peacebuilding with sustainable agriculture.

Castro, whose team has a wide body of research on successful silvopastoral systems and landscape restoration, said one obstacle is trying to change too much too quickly.

“Sometimes, in the development sphere, we want to make many changes instantly. But if you want to promote a very complex system that integrates six or seven new practices into a day-to-day work plan, it’s too complicated. A better approach gradually integrates new practices one at a time,” added Castro, pointing to work in Colombia, Peru and Africa.

Misalignment between the values of those who support research for development and on-the-ground scientists and beneficiaries may also be an obstacle.

“How can we connect the benefits that we want – social stability, climatic peace and environmental conservation and restoration – with benefits other countries desire?” Castro said. “Some are interested in reducing migration, for example, which, in theory, could result from obtaining the benefits we want.”

Other, little-explored externalities of the highly interconnected global food system may also need to be addressed to increase sustainability in agriculture. For example, Castro’s team recently published findings in Scientific Reports that revealed a strong correlation between deforestation and foreign direct investment in some developing countries.

“The influence of the Global North on the Global South is very powerful,” pointed out Castro, indicating how diets and consumer behavior in developing nations often mimic northern nations. “If richer nations begin setting better examples for sustainability, we might just follow suit.”

Castro said scientists identified many practical innovations to make livestock systems more sustainable. Current research focuses on the social, institutional, financial, and political factors needed for broader uptake. Key barriers include land-tenure disputes, limited investment, and limited farmer access to credit. “How can we reduce the cost of implementation? It’s expensive,” Castro said.

Arango, the Alliance forages lead scientist, outlined additional challenges facing the widespread adoption of grasses that reduce GHG emissions: a lack of technical assistance for farmers, poor links to carbon markets for livestock systems in the Global South, and the sheer size of the areas that could be transformed. “We’re talking about hundreds of millions of hectares,” Arango said. “You can’t change the grasses on all this land overnight.”

Even if all these issues were solved – and farmers were ready to widely adopt new grasses and practices tomorrow morning – there just isn’t enough seed. Yet.

“The biggest challenge is the amount of seed needed. We have a very high diversity but only in small amounts,” stated Gonzalez, the Alliance’s forage gene bank manager. “We need big companies to invest in doing their own research, or to finance ours, and mass-produce the seeds we have or are developing.”

About Sean Mattson
Sean Mattson is the Global Communications Officer for the Alliance of Bioversity International and CIAT, focusing on science communication for Alliance research across Africa, Asia, and Latin America. He joined the Alliance in 2018 after working as a science writer, photographer, and scientific diver at the Smithsonian Tropical Research Institute in Panama, where he documented the work of hundreds of scientists studying tropical ecosystems. Mattson began his career as a journalist in Mexico in 1999, contributing to several international publications and newswires. He was a Mexico correspondent for the San Antonio Express-News and worked for Reuters as a Central America correspondent in Panama.