It’s easy to ruminate over methane when thinking about dairy and its production challenges. Cattle are essential to Wisconsin’s $45.6 billion dairy community. But cattle have to eat — and when they eat, they produce the greenhouse gas methane during digestion.

This process is natural, but it’s not without problems. Individual cows emit 150 to 260 pounds of methane per year — primarily in the form of belches. Fortunately, there are ways to reduce the amount of methane that cattle burp up, and CALS scientists are using a grant from the Greener Cattle Initiative (GCI) to find them.

GCI is an international consortium of stakeholders that supports research on minimizing enteric methane production in dairy cattle. In September 2023, the initiative awarded a $3.3 million grant to Francisco Peñagaricano PhD’14, an assistant professor of animal and dairy sciences at CALS, for a project that takes a three-pronged approach to the challenge. His goals are to use genetics to selectively breed cattle that emit less methane, develop a milk-based test that can predict a cow’s methane emissions, and explore the rumen microbiome for possible dietary interventions.

“The Greener Cattle Initiative was launched to address the many challenges that remain in identifying, developing, and validating effective enteric methane mitigation options . . . that meet farmers’ and broad socioeconomic needs,” says Juan Tricarico, director of GCI and senior vice president of environmental research and distinguished scientist at Dairy Management Inc. “This project is important for long-term mitigation because selectively breeding low methane-producing dairy cattle is permanent and cumulative, and it will probably also be cost-effective.”

Peñagaricano is working with three other faculty from the Department of Animal and Dairy Sciences: Hilario Mantovani, who specializes in rumen microbiology; Kent WeigelMS’92, PhD’92, who focuses on breeding and genetics; and Heather White, who studies nutritional physiology. All four are affiliated with the UW Dairy Innovation Hub.

What Is the Dairy Innovation Hub?

The Hub, funded through a $7.8 million-per-year investment by the state of Wisconsin, harnesses research and development across the UW–Madison, UW–Platteville, and UW–River Falls campuses to ensure Wisconsin’s $45.6 billion dairy community remains a global pacesetter in dairy innovation.

Through multiple grants (including one to Peñagaricano), the Hub has helped CALS purchase two methane-measuring GreenFeed systems, bringing the university’s total to five. A GreenFeed device is a portable feeding bin that captures all the air exhaled by a cow while she is eating and delivers a reliable estimate of methane emissions for that individual cow. Peñagaricano cites the Hub support as a major factor in attracting the GCI grant.

A first step for the new GCI-funded project will be to develop a reference population of nearly 4,000 dairy cows. And the first research prong will be to look at the genetics of these animals, focusing on the natural methane-burping variability found in the group. All cows produce methane, but not every cow is alike. Peñagaricano’s prior research shows that some cows release around 600 grams of methane per day, while others average around 300 grams. For the GCI study, the cows in the reference population will undergo genomic evaluations for various methane emission traits, such as the quantity or frequency of production. Once these traits are better understood, the team can pursue selective breeding for cows that produce less methane.

“Variability is crucial, [and] part of that variability is due to genetics,” says Peñagaricano. “We can use that variation to improve cows in the next few generations through genetic selection.”

The second prong of the project explores milk testing. Generally, dairy farmers send monthly milk samples to a lab to monitor quality and to get an idea of protein and fat levels in the milk. Peñagaricano’s team envisions farmers also receiving a prediction of methane emissions from the herd. The new test would use milk spectrometry, which involves scanning milk samples with infrared light to identify specific chemical compounds. The goal is to develop a low-cost, noninvasive tool that farmers could potentially use at the national level.

“Let’s say the federal government or milk buyers say [farmers] need to minimize methane emissions, but first the farmers need to have an idea of which cows are emitting more, and which are emitting less,” says Peñagaricano. “And if they know which ones are emitting more, they can target those cows with interventions, such as specific diets, to minimize that.”

The third prong of the project focuses on the rumen, the digestive organ in cows that contains methane-producing bacteria. Not much is understood about the relationship between the rumen microbiome and methane production or how cow diet or genetics impact the process. Using emissions data from the GreenFeed systems, the team will identify the 10% highest methane-producing and the 10% lowest methane-producing cows in the reference population and sample their rumen microbiomes. The sampled microbiota will be evaluated for differences before testing the impact of microbial or dietary interventions.

“Being a part of a project this big is really challenging but, at the same time, really amazing,” says Mantovani, a Hub-funded faculty member who will lead the rumen microbiome studies. “It is an opportunity to have access to a very large number of animals and to do research that could have a real impact in changing management practices and developing new tools.”

Over the course of three years, Peñagaricano, Mantovani, and others in a team from multiple institutions and states will tackle the expansive project and deliver solutions with both short- and long-term benefits for farmers, the broader dairy community, and the environment.