Concerns Over Toxic Fescue: What You Need to Know

Stretching from the Ozarks to the Appalatians is America’s “fescue belt,” and this array of grasses poses a challenge for ranchers and farmers, as it can become toxic.

Tall fescue is the most widely planted grass in the world and is native to England, but is unimportant there. The seed was a contaminant in meadow fescue seed, nearly all of which was imported from England. Tall fescue use in the U.S. was not to any measurable extent until the early 1940s, with the release of two cultivars, Alta and Kentucky-31.

Alta is an ecotype selected in 1918 and was released cooperatively by the Oregon Agricultural Experiment Station and the U.S. Department of Agriculture in 1923 because of its winter hardiness, persistence and ability to remain green during the dry summers of western Oregon. Alta was quickly planted widely across the Pacific Northwest and in the intermountain regions of the western United States.

Kentucky-31 is an ecotype found growing in a steep mountain pasture of eastern Kentucky by Dr. E.N. Fergus, a professor at the University of Kentucky, who happened upon a pasture of the resilient grass in 1931 and secured some seeds for research. Struck by the grass’s ability to stay lush and green in the cold months, KY-31 was released as a cultivar in 1943 after extensive testing — heralded for its dependability, adaptability and year-round grazing capabilities.

The Dark Side of Tall Fescue

The history of tall fescue’s rise in the agricultural landscape is intertwined with the challenges it brings. Originally hailed for its resilience and year-round lush, green color, tall fescue’s dark side emerged in the 1950s as ranchers observed its effects on livestock.

The turf industry has widely adopted varieties of KY-31 tall fescue because of its durability, drought resistance and ability to withstand heavy traffic —  and it’s those same characteristics that have made it so widespread in grazing pressures for livestock. One of the notable characteristics of KY-31 tall fescue is its tolerance to various environmental conditions, including acidic soils and poor drainage. This made it an appealing choice for pastures and lawns in areas where other grass species might struggle.

However, KY-31 tall fescue contains a fungal endophyte that produces toxins called ergot alkaloids. These alkaloids, while beneficial for the grass in terms of pest resistance, are harmful to livestock if consumed in large quantities. Grazing animals that consume significant amounts of ergot alkaloids experience health issues such as reduced weight gain, poor fertility and vasoconstriction (constriction of blood vessels).

Researchers estimate about 85% of the more than 40 million acres of tall fescue in the United States contains endophyte-infected fungus that causes the poor performance and health problems in beef and dairy herds.

The symptoms of fescue toxicosis in cows begins with lameness in one or both hindfeet and may progress to necrosis of the distal part of the affected limbs. The tail and ears may be affected independently of the lameness, and in addition to gangrene, sick animals may show loss-of-body mass, an arched back and a rough coat. Fescue toxicosis costs ranchers approximately $2 billion, annually 

Efforts to engineer an endophyte-free version of the hearty grass led to underwhelming results, leaving toxic fescue as the dominant pasture grass across tens of millions of acres.

Toxic Fescue Is Spreading

Climate change adds another layer of complexity, expanding the fescue belt’s reach as toxicosis creeps into new regions. Rising temperatures have pushed the grass northward, encroaching on previously unaffected areas like northern Illinois and southern Iowa, underscoring the urgency of finding effective solutions to mitigate the impacts of toxic fescue.

Various remedies, such as dietary supplements and seasonal clipping of the toxic seed heads, have long been used in an ad-hoc fashion, yet none have been universally successful.

Potential Remedies

Two strategies have emerged to fight the fescue dilemma and, of course, they’re diametrically opposed. One approach is planting the modified, or “friendly fescue,” with its benign endophytes that retain the grass’s color and resilience without the toxicity.

Research has shown the introduction of novel endophyte tall fescue (NETF), a variety of the non-toxic forage that eliminates the toxins at the source, offers consistent benefits without ongoing costs, presenting a long-term solution for cattle producers grappling with fescue toxicity.

“The NETF checks all the boxes,” Craig Roberts, a forage specialist at the University of Missouri, told Farmers Hot Line. “It’s much better than any other cool-season grass in this part of the U.S. and the closest thing to a silver bullet available.”

The other potential solution proposes a shift away from fescue altogether, restoring native grasses and wildflowers to revive biodiversity and the natural carbon sinks. However, this option is unappealing to some because of the missing lushness of the brown, native species in the winter months. 

While both strategies have merits, adoption remains slow due to cost and cultural factors. Friendly fescue, despite its benefits, comes at a higher cost and requires labor-intensive pasture conversions and while this additional cost and inconvenience can be overcome, it only adds to the reluctance of farmers and ranchers to embrace change thanks to past disappointments.

Amid these debates, some are forging their own path by transitioning to native grasslands. Proponents argue that the benefits, such as increased water infiltration, improved soil health and reduced reliance on supplemental feed, can compensate for the additional costs. Native grasslands also excel in carbon sequestration, playing a crucial role in mitigating climate change’s impacts on agriculture.

However, Roberts suggests an approach that encompasses all of the strategies for managing toxic fescue. 

“Ideally, we’d be able to replace KY-31 with NETF,” he said. “But until then, toxicosis can be managed by interseeding legumes such as clover, limiting nitrogen-heavy fertilizer, adding ammoniated hay and by avoiding grazing low in the fall.”

Dilution and Supplementation

The most common approach in the fescue belt has been to dilute the infected KY-31 pastures with common grazing legumes, such as red and white clover, birdsfoot trefoil, annual lespedeza and alfalfa. Each of these legumes differs in persistence, but all can be maintained with proper management and naturally mitigate the chemistry of tall fescue toxicosis. Supplementing with corn or other feeds can also reduce the toxic effects of the endophyte on cattle if fed at a rate of 0.6% of body weight.

Close Grazing

If fescue toxicosis is more of a concern than forage yield, graze infected KY-31 tall fescue closely. When it is allowed to develop seed heads, it becomes more toxic because the grass’s seed heads contain much more ergovaline and mature tall fescue contains less protein and more fiber than leafy, immature fescue. By seasonally removing the heads, pastures can be made less-toxic with minimal labor and cost.

Ammoniation

Ammoniation is the covering (with tarps) and treating of hay with ammonia, which breaks the cell-wall linkages in the hay, increasing digestibility. Research conducted at the University of Missouri showed that treating low-quality hays with ammonia, can increase daily gains and prolactin (a dairy cow’s milk hormone) levels by 50%. Low-quality tall fescue hay is ideal for ammoniation; however, if the hay is high quality, it can become toxic after ammonia treatment and cause crazy cow syndrome. 

Navigating the Dilemma

The debate over toxic fescue encapsulates broader themes in ranching and agriculture, from adaptation to climate change, while fighting a culture of mistrust toward authorities. 

As ranchers navigate these challenges, the need for collaboration to maximize technological advancements, ecological restoration strategies and cultural shifts necessary have never been more important.