ID-221: Fescue Toxicosis in Cattle

Megan Romano, Michelle Arnold, Ray Smith, Krista Lea | Feb. 13, 2025 (Minor Revision)

Tall fescue [Lolium arundinaceum (Schreb.) Darbysh., previously known scientifically as Schedonorus arundinaceus (Schreb.) Dumort.] is a cool-season, perennial grass (Figure 1). The Continental type, most notably the Kentucky-31 variety, is frequently infected with an endophyte (Epichloë coenophiala). An endophyte is a fungus that grows inside the grass, specifically within the intercellular spaces of the leaf sheaths, stems, and seeds, and is invisible to the naked eye. The plant and fungus have a mutually beneficial relationship, wherein the plant provides the fungus access to its nutrients and a means of asexual reproduction through infected seeds. In turn, the fungus produces compounds called ergopeptine alkaloids that increase the plant’s vigor by making the plant more pest- and drought-resistant and more tolerant of other adverse soil and environmental conditions. Although advantageous to the plant, ergopeptine alkaloids adversely affect the health and productivity of grazing livestock. Ergovaline is the most abundant (more than 90 percent) and most toxic ergopeptine alkaloid in endophyte-infected (E+) tall fescue. The highest alkaloid concentrations are found within the seedheads and in the bottom few inches of the plant.

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ID-217: Forage-Related Disorders in Cattle: Nitrate Poisoning

Michelle Arnold, Jeff Lehmkuhler, Megan Romano, Ray Smith | Oct. 24, 2022 (Minor Revision)

Nitrates are natural constituents of all plants. Under normal conditions, plants take up nitrate through their roots and transport it to the leaves for use in photosynthesis. However, photosynthesis decreases under adverse environmental conditions (e.g., drought; leaf damage due to disease, hail, frost, insects, or herbicides; cool and cloudy weather; and other plant stressors). When photosynthesis is reduced, nitrate transportation to the leaves slows also. Potentially toxic nitrate concentrations can remain in the lower stalks and stems.

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ID-2: Guide to Plants of Kentucky Potentially Poisonous to Livestock

Michelle Arnold, J.D. Green, Megan Romano | Apr. 22, 2022 (Minor Revision)

Poisonous plants are responsible for considerable losses to farmers and stockmen in Kentucky. Many cases of plant poisoning are never diagnosed or even suspected. There are nearly 100 different species of plants growing in Kentucky that under certain conditions may be poisonous to livestock, although only one third of these are likely to cause serious trouble. The primary purpose of this publication is to enable individuals to recognize, at sight, some plants which are known to be dangerously poisonous, and to have knowledge of those additional plants, which, under certain conditions, may cause trouble.