A new free modeling tool is enabling researchers, farmers and food processors to assess how changes in the ways a dairy farm is managed would influence its environmental impact, energy use and economics. The Ruminant Farm Systems (RuFaS) modeling tool, developed by Cornell researchers and collaborators across academia, industry, government and nonprofits, is available at no cost for open-source collaboration.
Cornell researchers created the scaffolding for the model and worked with collaborators to integrate Cornell and other dairy farm research on factors like animal feed, crop growth and milk production. The model predicts outcomes such as production costs, resource use and greenhouse gas emissions.
Cornell's Department of Animal Science in the College of Agriculture and Life Sciences (CALS) has led development of the model, with support from the College of Veterinary Medicine (CVM) and Cornell Atkinson Center for Sustainability.
The model synthesizes a vast array of factors and can accommodate additions of new research from multiple collaborators, said Daryl Nydam, professor of dairy health and production in CVM.
"If you're trying to make a decision about feeding cows, or the reproduction cycle or the nutrient cycle, you can run those decisions through this model and try it there, without mucking up the farm," Nydam said.
For example, the model could be used to assess manure and fertilizer management, said Elle Andreen, model support specialist with PRO-DAIRY, a Cornell extension and applied research program (CALS).
"RuFaS uses the information from your farm to represent your animals, your manure system, your field and crops, and your feed storage, as closely to reality as possible," Andreen said. "And then it allows you to change any of that information to understand what would happen if something were different. RuFaS is so multifaceted, farmers and researchers can use it in many ways to support their needs."
Farmers are already using the model across the country. The National Milk Producers Federation and Dairy Management, Inc. (DMI) has adopted it as the model for its environmental stewardship assessments program, the National Dairy Farmers Assuring Responsible Management (FARM) said Nicole Ayache, chief sustainability officer for the National Milk Producers Federation. Thanks to the integration, all U.S. dairy farmers can now access the RuFaS model, she said.
Since October 2025, 215 farms across 20 states have used RuFaS via the FARM interface, ranging from 30-cow to 14,000-cow operations, she said. The code underlying RuFaS is now available, open-source, for other researchers and organizations to build upon.
Kristan Reed, formerly an assistant professor of animal science at Cornell and research scientist with the U.S. Department of Agriculture, said RuFaS is "like SimCity but for dairy farming." Reed, now a freelance consultant, has been the driving force behind RuFaS since its inception and still leads the model's development.
"We wanted to build a better dairy farm simulation model that was more flexible, able to represent a wider range of management practices and able to be used by a wider set of people, including scientists and people in the dairy industry," she said.
Previous models were more limited in scope, or based on older coding technologies, which hampered collaboration and the addition of new information, Reed said. Developing such an intricate and multi-faceted model has taken almost eight years, public and private funding support and close collaboration between more than 20 organizations, institutions and companies.
Cornell Atkinson's investment in RuFaS, through funding, advice and operational guidance, demonstrates how academic excellence can translate into actionable solutions, said Patrick Beary, senior director of strategic partnerships at Cornell Atkinson.
"When consumers choose that glass of milk, wheel of cheese or scoop of ice cream, they're benefiting from the sustainable decision-making that tools like RuFaS make possible," he said. "This is research in its most impactful form: science serving dairy farmers who provide nutritious food and influence the health of our planet."
Krisy Gashler is a writer for Cornell Atkinson Center for Sustainability.
