When it comes to grass with both benefits and drawbacks, tall fescue takes the cake.
Introduced to the United States from England in the late 1800s, tall fescue is incredibly hardy and drought-resistant, thriving in a wide range of temperatures. As a cool-season grass, it offers a reliable source of forage year-round and even stays green into the winter in many areas. However, its resilience comes with a significant downside—it’s often low in nutritional quality and can pose serious health risks to cattle due to its toxic properties.
Where is Tall Fescue Found in the United States?
According to the University of North Carolina and the University of Missouri, over 40 million acres of tall fescue grow across the United States. The dominant variety, known as Kentucky-31 (K-31), stretches from the Eastern U.S. to Oklahoma, an area often called the “fescue belt.” This region contains roughly 25% of the U.S. beef cattle population, making the impact of fescue toxicity a major concern for producers.
What is Fescue Toxicity in Cattle?
Fescue toxicity is a condition caused by the ingestion of toxic compounds found in tall fescue grass, particularly the dominant variety known as K-31.
The problem lies in a fungal endophyte (Neotyphodium coenophialum) that lives within the grass. While this fungus strengthens the grass, making it more durable and resistant to harsh conditions, it also produces ergot-alkaloid compounds. These compounds are toxic to cattle and can lead to a range of health issues, collectively referred to as fescue toxicity.
Symptoms of Fescue Toxicity in Cattle
Decreased feed intake and weight gains
Rough hair coats
Shortened tails and delayed shedding of winter hair
Slow breed-back rates
Severe lameness and “fescue foot” (in extreme cases, hooves may fall off)
Low tolerance for heat stress
The toxin acts as a vasoconstrictor, limiting blood flow and causing widespread issues in the body.
How Fescue Toxicity Affects Cattle
When blood flow is restricted, cattle face challenges similar to those seen in humans with diabetes. Poor circulation limits the delivery of essential nutrients to key areas like hair and hooves. In cattle affected by toxic fescue, this results in rough coats, shortened tails and lameness, as the hooves and hair are deprived of the nutrients they need to remain healthy.
Fescue toxicity also makes it harder for cattle to manage heat stress. Cattle already struggle to dissipate heat, sweating at just 10% the rate of humans. When affected by fescue toxicity, they cannot effectively push blood to their extremities to cool down, leading to symptoms like panting, drooling and increased susceptibility to heat.
Additionally, animals are also more likely to experience disease and infection, as fescue toxicity weakens their immune systems.
Cow showing symptoms of fescue toxicity with a rough hair coat.
The Immune Impact of Fescue Toxicity and the Role of Oxidative Stress
Interestingly enough, cows can actually detox themselves from fescue to varying degrees. However, this detoxifying process results in significant oxidative stress, creating its own set of issues that need to be addressed.
Oxidative stress is caused by the imbalance of excess free radicals in the body. Free radicals are naturally occurring and are utilized by the immune system to fight disease as well as normal metabolic function. But, during times of stress (environmental, nutritional or, in this case, fescue toxicity), too many free radicals are produced, and they begin harming sensitive tissue and molecules that are necessary for optimal performance in cattle.
How to Manage Fescue Toxicity in Cattle
There are three primary ways to help cattle manage fescue toxicity.
1. Dilute Fescue Pastures
To lower the levels of toxins and tall fescue in one location, it's important to start seeding pastures with a variety of grasses. This will help dilute the level of toxins cattle ingest. It is suggested to plant legumes, such as clovers and alfalfa. Legumes are warm-season grasses that can help dilute pastures while adding nitrogen back into the soil.
2. Don’t Let Fescue Grass Go to Seed
The most poisonous part of fescue grass is the seed head. It is recommended to graze these fields hard to prevent grass from going to seed. Otherwise, mow it regularly. If you plan to bale fescue, do so before it goes to seed. Otherwise, you will continue to see fescue toxicity into the winter.
3. Incorporate Antioxidants, Essential Oils and Trace Minerals
Antioxidants are proven to help lower oxidative stress. As stated above, oxidative stress causes an imbalance of free radicals. Free radicals are atoms that have an uneven number of electrons. They are on the hunt for an additional electron to balance the atom, and they will steal an electron wherever they can find one, including from cells that promote immune function and tissue growth. Natural vitamin E, essential oils and trace minerals are proven to reduce free radical damage and support immune function.
The Importance of Antioxidants and Why Essential Oils Outperform Traditional Options
Antioxidants are molecules capable of slowing or preventing the oxidation of other molecules because they can share electrons and reduce free radicals. There are many antioxidant options today -- including natural vitamin E, trace minerals and essential oils. However, the effectiveness of available options varies significantly.
Oxygen radical absorbance capacity (ORAC) is a method used to determine the antioxidant capacity of a given compound. Vitamin E has an ORAC score of 48,200 while Ralco’s essential oils have an ORAC score of 2,349,200 - 40 times greater than vitamin E. Additionally, research shows that essential oils are vasodilators and can help increase blood flow and heat dissipation in cattle under heat stress.
Trace minerals also have antioxidant properties to help lower oxidative stress and support challenges in reproduction and immunity that are amplified with fescue toxicity.
Need Help with Fescue Toxicity?
Ralco’s Rumatec Cow-Calf Mineral is specially designed to combat the challenges of fescue toxicity. With balanced trace minerals and the essential oil additive Comfort included, Rumatec helps:
Manage oxidative stress and fescue toxicity
Improve heat tolerance
Support reproductive and immune health in cattle
Schedule a FREE consultation with a ruminant nutritionist today by calling 507-337-6916 or emailing RuminantHelp@RalcoAgriculture.com
Rumatec - Cow/Calf Mineral
The Rumatec line of cow/calf supplements provides the needed nutrients commonly deficient in forages to help ensure optimum performance and reproductive efficiency.
Comfort - When the Heat is On
Comfort is an everyday feed additive containing a custom blend of essential oils and capsicum for targeted support and animal comfort during times of environmental challenge.