How to Prevent Fescue Toxicosis in Broodmares
Tall fescue is a hardy, nutrient-rich forage found on 40 million acres across North America. This pasture grass, however, can cause fescue toxicosis in pregnant mares, leading to pregnancy losses and reduced reproductive efficiency. So, breeders go to great lengths to keep late-term broodmares off tall fescue. It’s most prevalent in temperate southern regions.
An endophyte (a fungus that lives within a plant) called Neotyphodium coenophialum, pictured at right, infects certain tall fescue varieties and produces the alkaloid ergovaline. The endophyte has a symbiotic relationship with tall fescue: The plant provides the endophyte a place to thrive, while alkaloids make tall fescue insect-resistant and drought- and grazing-tolerant. Unfortunately, it can also cause narrowing of blood vessels, leading to serious livestock reproductive issues. In horses, specifically, ergovaline exposure can cause fescue toxicosis.
Signs of Fescue Toxicosis in Pregnant Mares
How to Avoid Fescue Toxicosis

Take-Home Message:

Consider all tall fescue endophyte-infected unless proven otherwise. If you have concerns about fescue toxicosis, your veterinarian and local extension specialist are your best sources of information specific to your region.