Stockpiling Fescue Grass for Winter Reduces Toxicity Levels

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A retired professor of toxicology at Oregon State University, Dr. A. Morrie Craig leveraged more than four decades of experience in the field of veterinary toxicology to teach students at the institution’s veterinary school. In addition to teaching, Dr. Morrie Craig also led the endophyte laboratory at the school, and completed several research projects related to toxic grass and grazing animals.

Endophytes live between living plant cells. These organisms are usually bacteria or fungi, and will establish various types of relationships with the plants, ranging from symbiotic to pathogenic. Grass, and particularly tall fescue grass, is one plant that maintains a symbiotic relationship with certain endophytes, known as alkaloids. This type of grass covers about 37 million acres in the United States, making it the world’s most widely grown perennial grass thanks to its drought resistance and winter hardiness.

Unfortunately, fescue that is infected with ergot alkaloid, a specific type of endophyte, is detrimental to grazing animals, like cows and horses. When consumed in high levels, the toxin limits blood circulation and causes frozen feet and lower levels of conception in cattle and other grazing animals.

Typically, toxin levels in fescue grass are highest during the spring growth period. The grass goes through a second growing season in the fall after experiencing a growth slump in summer. During this season, fescue only grows leaves, not seed stems. However, the leaves also contain ergot alkaloids, so the grass is still toxic.

To reduce toxicity, farmers should begin stockpiling fescue grass in August, once is is well into its lower-growth stage. Toxic alkaloids are lowest during this time, thus helping farmers feed their grazing animals with less risk to their health during the winter. However, the toxin does still exists, so it’s preferred that farmers grow novel endophyte or endophyte-free varieties instead.