Fall 2019

On Henry Mall

One way the Dairy Coordinated Agricultural Project, or Dairy CAP, has distributed its findings is through the Virtual Farm website, which is hosted by project partner The Pennsylvania State University. The site demonstrates the typical operations of both large and small dairy farms and ways that dairies can reduce their impact on the environment. Photo courtesy of Dairy CAP

In 2013, the $10 million Dairy Coordinated Agricultural Project, or Dairy CAP, set out to assess the greenhouse gas contributions of the dairy industry and help farmers meet the industry’s goal to cut greenhouse gas emissions by 25% by 2020 while maintaining or boosting profitability. Six years later, the project has wrapped up with a set of promising solutions.

The Dairy CAP’s recommendations center on efficiency. Researchers found that a combination of improved animal husbandry, different feeding strategies, and better manure management could allow dairies to cut emissions by a third to almost half while producing more milk with less feed to ensure economic feasibility.

CALS professors Matt Ruark and Molly Jahn led the Dairy CAP in collaboration with seven other universities, the U.S. Department of Agriculture (which funded the project), and the Innovation Center for U.S. Dairy, an industry-supported research group. The team issued its final report earlier this year.

“I think there are three big takeaways,” says Ruark, a professor of soil science. “One, efficiency in milk production leads to reduction in greenhouse gas emissions. Two, reductions in greenhouse gases can be achieved along with reductions in nutrient loss and increases in economic returns. And three, dairy-based cropping systems can be adaptive to climate change.”

Milk production emits greenhouse gases from three primary sources: methane produced in the rumen; emissions during manure storage and spreading; and the emissions associated with growing crops for feed. Methane — an inevitable byproduct of ruminant digestion — is 25 times more effective than carbon dioxide at trapping heat in the atmosphere. Nitrous oxide, derived from manure and fertilizer applications, is 10 times more potent than methane.

The Dairy CAP team tracked emissions at each of these stages. Experimental modifications were followed throughout their entire life cycle to identify how, for example, feed changes affected not just the production of milk and methane but manure emissions and the growth of crops fertilized with that manure.

Experiments were conducted at the UW–Madison Dairy Cattle Center, the UW Arlington Agricultural Research Station, the USDA Dairy Forage Research Center in Prairie du Sac, Wisconsin, and at partner institutions. The experiments helped refine feed-to-manure computer models of emissions and economic returns for both 150- and 1,500-cow dairies.

The benefits from using the best cow genetics, feed practices, manure handling, and cropping systems added up quickly.

“If we implement these best management practices, we’re going to reduce greenhouse gas emissions by 36% [for a 1,500-cow dairy],” says Ruark. “At the same time, we’re going to reduce nitrogen losses to groundwater by 41%. We’re going to reduce phosphorus losses to surface water by 52%. And we’re going to increase net return 20%.”

Similar practices could drop greenhouse gas emissions by 46% for 150-cow dairies, the researchers found.

One of the most effective ways to cut emissions is to use an anaerobic digester to convert the methane from stored manure into carbon dioxide. While this is an expensive solution, the costs could be partly offset by generating and selling electricity from burning the methane or converting it into compressed natural gas to fuel cars and trucks.

Yet changing practices to cut emissions could be a tough sell as dairies continue to struggle through a years-long slump in milk prices, says agricultural and applied economics professor Mark Stephenson. An expert in dairy economics, Stephenson helped create a tool to evaluate alternative manure management practices for the Dairy CAP. Low milk prices are a major reason why 800 Wisconsin dairy farms have closed since August 2018.

“One of the legs of sustainability is economic,” says Stephenson. “Just because you want to reduce greenhouse gases doesn’t mean that you can afford to employ the best practices. The efficiency gains are key to the adoption.”

That efficiency stems from improving the conversion of feed into milk through feeding practices and dairy cow genetics. These best practices can reduce costs for farmers and emissions from milk production. Researchers also assembled recommendations to help farmers adapt to a warming climate, such as ways to predict the ventilation needed in a barn to keep cows cool.

The project’s findings have been distributed through fact sheets published by the Division of Extension and on the Virtual Farm website hosted by The Pennsylvania State University. The site demonstrates the typical operations of both large and small dairy farms and ways that dairies can reduce their impact on the environment.

The Dairy CAP also looked toward the next generation. Project leaders partnered with Milwaukee’s Vincent High School to help revive its original design as an agricultural school. The grant paid for agriculture outreach specialist Gail Kraus to join the school’s staff and help design a new agricultural curriculum with six specialties.

“I had come to understand that to really enrich our campus environment we had to be active at the secondary and elementary level to open pipelines of students for college,” says Jahn, who initiated a relationship with the school eight years ago.

The agricultural revival grew from teachers interested in teaching aquaculture and developed to include courses in the animal and plant sciences. Students were aided by an existing greenhouse and the addition of a menagerie of chickens, ducks, cows, and goats. They went on to show lambs at  the 2018 and 2019 Wisconsin State Fairs. The grant also provided funds for students to attend pre-college programs at the University of Illinois at Urbana-Champaign.

“The Dairy CAP was a really exciting opportunity to work cooperatively with about 100 scientists all over the country,” says Carolyn Betz, the project manager and author of the final report.

She recognizes that the challenges facing dairy farmers today may make it hard to quickly adopt new management practices. But Betz sees opportunity as dairies inevitably update their operations over time.

“When farmers are making changes anyway, we hope they’ll incorporate these solutions,” she says.

To read the final report for the Dairy Coordinated Agricultural Project, visit

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