The pursuit of a low-emissions cow

NAIROBI — Researchers are on the hunt for a cow that produces less methane, one of the major contributors to climate change. If and when those green genes can be easily isolated, they could be spread throughout global cattle populations.

The livestock sector accounts for an estimated 14.5 percent of human-related greenhouse gas emissions globally, with about 44 percent of those emissions in the form of methane, according to the U.N.’s Food and Agriculture Organization. Methane is a byproduct of livestock digestion and manure emissions, among other sources. Cattle account for the majority of the sector’s contributions, adding to about 65 percent of emissions.

While methane has a shorter lifetime in the atmosphere than carbon dioxide, it is more effective at trapping radiation. This makes its impact over a 100-year period more than 25 times greater than carbon dioxide, according to the U.S. Environmental Protection Agency.

Scientists see urgency in addressing methane emissions now. Rates are slated to rise rapidly as developing economies grow. Lifestyle and diet changes, coupled with population growth, are expected to more than double the demand for animal-based products by 2030, according to the FAO.

Changing consumption may prove impossible, so internationally, researchers have been working on changing the cow. A newly created collaboration led by the Global Research Alliance on Agricultural Greenhouse Gases is one of the latest efforts. It will work to study the microbial communities of the stomachs of cattle, hoping to identify those with lower methane emissions. The sampling is expected to take place in countries including Australia, Denmark, Scotland, Uruguay, and Brazil, but the extent of the partnerships has not been finalized. If and when favorable genes can be easily isolated, the long-term aim will be to provide farmers with the tools to integrate this trait into its breeding programs for cattle.

“We are in the early days of conceptualizing and doing this research,” said Jimmy Smith, director general of the Nairobi-based International Livestock Research Institute. “Looking for this low-emissions cow is one of the long-term dreams I have.”

A climate-friendlier animal may be available to farmers in a few years in developed countries such as New Zealand, but it could be decades before the developing world sees these breeding gains. In the meantime, development agencies, governments, and farmers are pushing to increase the productivity of livestock, which also helps mitigate methane emissions.

Identifying the low emitters

For some years now, research institutes have been studying low-emitting ruminants among livestock populations. If they are able to easily identify and make the breeding of the trait economical, these low-emitting animals could be naturally bred into the population and their semen could be sold to farmers for use in artificial insemination in the larger population.

For example, starting in 2007, the Pastoral Greenhouse Gas Research Consortium and Sustainable Land Management and Climate Change funded a study that found that methane emissions was a heritable trait in sheep, offering the opportunity “for genetic selection as a potential option to reduce CH4 yield emissions.”

Animals have traditionally been tested in respiratory chambers, which are large boxes where the animals are placed and then the methane content in the air is measured. But that process is time-consuming and costly. The chambers used for cows are larger than they are for sheep, and as a result, countries such as New Zealand have fewer of them. Sheep also breed faster, making them more suitable for gathering large amounts of evidence for genetic studies. As a result, sheep have been studied more closely.

Now there are efforts to identify low-emission cattle by examining the microbial content in the animal’s rumen, which is one of the chambers of its stomach that contains a mixture of methane and non-methane generating bacteria. Ruminant animals, such as cattle, goats, sheep and buffalo, have a stomach with four chambers. Methane is produced in the intestinal fermentation process in the animal’s rumen. A microbial group in the rumen harnesses excess hydrogen and emits methane as a waste product.

A global collaboration, through the Global Research Alliance on Agricultural Greenhouse Gases, was recently launched, aimed at gathering microbial samples from cattle around the world in countries that could include Australia, Denmark, Scotland, Uruguay, and Brazil. The New Zealand Agricultural Greenhouse Gas Research Centre would then analyze these samples.

When the right characteristics are identified, a low methane-emitting cow could potentially be found using a mouth swab — a technique easy enough to be used to identify the large quantities needed to have a successful breeding program. The project aims to develop a tool to identify the lowest emitters in any herd or flock, so that those traits can be prioritized in any breeding effort if desired using existing gene pools.

The research collaboration will tap into other ongoing global studies working to identify the low-methane trait. Countries across the European Union are collecting small datasets of methane emissions of ruminants. The METHAGENE network is working on the best ways to harmonize the data so that datasets can be combined. The Efficient Dairy Genome Project, through the University of Alberta and University of Guelph, is also collecting data on the low-methane trait, among other global efforts.

Selecting animals with lower methane byproducts could reduce emissions by up to 5 percent, but this percentage could rise to 10 or 20 percent if it becomes a breeding objective over several decades, according to the Global Alliance for Climate-Smart Agriculture.

In countries such as New Zealand, farmers might have the option to purchase semen from low-emitting cattle in just a few years, said Andy Reisinger, deputy director of New Zealand Agricultural Greenhouse Gas Research Centre.

But funding for the research does stand as a barrier. The scale and scope of this research will be determined by funding, Reisinger said. The Global Research Alliance on Agricultural Greenhouse Gases is still identifying funding sources and agencies that will contribute to the work. An estimated $150,000-350,000 is needed annually for three years to bring countries with existing research capacities on board.

Getting farmers on board

If researchers succeed in pinpointing lower-emission cattle, farmers would have the option to purchase the semen of low-emitting cattle. Farmers typically choose among an index of traits, such as disease resistance. The economic value of the trait usually drives the emphasis in selecting traits, said Suzanne Rowe, senior scientist of animal genomics at AgResearch Ltd. in New Zealand. Research is still needed to determine if the low-emissions trait could have an impact on animal efficiency or productivity.

While the monitoring is ongoing, there have been only positive traits identified in sheep, such as higher production of wool, as well as preliminary evidence indicating the meat is leaner, said Rowe, senior scientist of animal genomics at AgResearch.

But even if the low-methane trait is available, farmers would need to be convinced that integrating it is a worthwhile addition to their breeding programs, Reisinger said.

Some possible strategies could include placing a price premium for selling climate-friendly meat or placing regulatory pressures on farmers, through something like a ‘carbon tax’ for meat, he said. There could also be a certification process for climate-friendly animal products.

“The farmer doesn’t get paid or fined for lower or higher-emitting animals. There is no incentive,” said Dr. Yvette de Haas, senior scientist for animal breeding and genomics at Wageningen University & Research.

An idling car

A low-emissions cow populating pastures in the developing world in the near future might be a pipe dream, said John Goopy, research scientist in livestock greenhouse gas measurement and mitigation at the International Livestock Research Institute in Nairobi, Kenya.

Advanced breeding schemes are scarce in the developing world, where breeding is generally more random, he said.

“It’s pretty unlikely that they are going to get to that stage of complexity, sophistication in the next 20 years,” he said. Because of this, it is more practical to push to increase the productivity of existing livestock, which in turn will reduce emissions.

In the developing world, there are huge gains to be made in increasing productivity in the livestock sector, which is where the research at ILRI focuses.

Some 80 percent of farmland in sub-Saharan Africa and Asia is managed by small scale farmers, which tend to operate with lower productivity, meaning fewer liters of milk produced as compared to countries like the United States, said Smith of ILRI.

Bringing highly productive breeds of livestock, such as the Holstein Friesian cattle, to developing countries is a tactic that has been used to increase productivity. But these temperate environment animals don’t thrive in the hot, humid tropics, which is where the majority of beef and dairy cattle are located. As a result, the approach by organizations like the ILRI has pivoted to cross-breeding among local genotypes, looking for improved performance.

Crossbreeding beef and dairy cattle from temperate regions, with local breeds for heat tolerance and disease and parasite resistance can lead to improved productivity, according to a 2016 report from the Global Alliance for Climate-Smart Agriculture. Improved dairy cow productivity in the United States over the past 60 years has led to a more than 40 percent reduction in methane, per unit of product, according to the report.

In August for example, a $12.6 million public-private development partnership was announced to improve milk yields per cow by at least 50 percent to 100 percent for 30,000 Kenyan dairy farmers. Partners include Heifer International, the Swedish International Development Cooperation Agency, the Tetra Laval Group, and New Kenya Co-operative Creameries.

Part of the program will include training on artificial insemination for cross-breeding local cows with the genes of cows that produce more milk. The project will also use climate-smart forage species for feed, including Brachiaria or "signalgrass," which is a “carbon sink,” absorbing carbon dioxide from the atmosphere.

“If an animal that produces two liters [of milk] now, can produce 10 liters in the future, it means that the emissions per unit of product goes down significantly,” said Smith.

When a cow is emitting large quantities of methane just to maintain itself rather than producing milk, it’s comparable to letting a car idle, Goopy said. Fumes are emitted but no distance was traveled.

“Ideally, you want to be zooming down the highway,” he said.

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