All parts of the plant, whether green or dry, may contain the alkaloid poison at any time of year. Symptoms include poor weight gain, lower pregnancy rates, and decreased milk production.
Tall fescue is palatable to livestock when the leaves are young.
Some commercially available varieties are more palatable than others. However, elk ate tall fescue in the Mount St. Helens area during October and November 1985. Forbs and shrub species dominated their summer diet, but grasses were selected in greater proportion than their relative abundance in the fall. Reports of tall fescue palatability for deer vary. Tall fescue nutritive value drops during its summer dormant period.