According to University of Kentucky experts, beef producers across the Eastern United States lose an estimated $2 billion each year to fescue toxicosis, a condition caused by cattle eating tall fescue infected with a toxin-producing fungus. Heat stress piles on another $370 million in losses. Now, a new research project involving the Martin-Gatton College of Agriculture, Food and Environment (CAFE) is asking whether alfalfa, long prized as livestock feed, might also be part of the solution.
The three-year study, which runs through September 2028, brings together researchers from Martin-Gatton CAFE, the USDA Agricultural Research Service's Forage-Animal Production Research Unit (FAPRU) and Auburn University. The project is directed by Brittany Davis, Ph.D., a research animal scientist with FAPRU, with UK contributing much of the animal, plant and Extension work.
"Alfalfa, both today and over the last 3,000 years, has been the most important, most valuable forage crop in the world," said Department of Plant and Soil Sciences Extension professor Ray Smith, Ph.D., who serves as UK's principal investigator on the project. "It's often called the Queen of the Forages, with corn silage being the King of the Forages. Alfalfa is known to be an outstanding crop for how much it can produce and how nutritious it is for animals."
The new study takes that reputation a step further.
"We're realizing that alfalfa has compounds that make it more than just a feed," Smith said. "You can think of it as a nutraceutical or what we call a functional feed-one that supports animal health beyond simply meeting nutritional requirements."
Tall fescue is the workhorse pasture grass across much of the Eastern U.S., covering roughly 35 million acres. The problem is that nearly 95% of that fescue carries an endophytic fungus that produces ergot alkaloids. When cattle eat the infected grass, the alkaloids constrict blood vessels, making it difficult for the animal to shed heat, eat well, gain weight or reproduce.
Add a hot, humid Kentucky summer, and the effects only get worse.
"Fescue toxicosis and heat stress compound each other, especially here in the Southeast," Smith said. "Producers have been asking for practical solutions for a long time, and we think alfalfa has real potential."
Bioactive compounds under the microscope
Alfalfa contains a group of natural plant compounds called flavonoids. Preliminary work by the UK and FAPRU team suggests those compounds can relax blood vessels, improve blood flow and help cattle better tolerate heat-the opposite of what fescue toxins do.
The project has four main goals. First, the team will test which specific alfalfa flavonoids, and at what doses, most effectively prevent fescue toxicosis in cattle. Second, researchers will profile flavonoid concentrations across alfalfa varieties grown in Kentucky and Alabama, looking at how genetics, plant maturity, plant part and environmental conditions influence the compounds. Third, they will feed whole alfalfa to beef steers during controlled fescue toxicosis and heat stress challenges. Finally, an Extension component will translate the findings into practical recommendations for producers.
Alfalfa production has historically been concentrated in the Western and North-Central U.S., with limited adoption across the Southeast. Demonstrating a new, high-value use for the crop could give regional producers a reason to plant more of it-and potentially reduce their reliance on nitrogen fertilizers along the way. UK experts currently encourage frost seeding red and white clover into pastures to reduce fescue toxicosis and alfalfa would provide a useful option.
Much of the animal work will take place at UK's C. Oran Little Research Center in Versailles under the direction of Ronald Trotta, Ph.D. with the Department of Animal and Food Sciences. Jeff Lehmkuhler, Ph.D. and David Harmon, Ph.D. will also contribute to Extension and research efforts. The alfalfa variety trials will be conducted at UK's Spindletop Farm and the Auburn University E.V. Smith Research and Education Center in Shorter, Alabama.
"If we can show that alfalfa helps cattle stay cooler and healthier on fescue pastures, that gives forage producers a real incentive to expand acreage in this part of the country," Smith said.
This material is based upon work supported by the Agricultural Research Service, U.S. Department of Agriculture, under Agreement No. 59-5042-6-002. Any opinions, findings, conclusions or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture.
