Fescue for Pregnant Mares

You want your broodmare to carry her foal safely to term and deliver a healthy foal. However, the pasture she is grazing on may be causing problems for the developing foal even if other horses on the pasture are unaffected. Fescue might be hurting your pregnant mare.

  1. Definition

    • Fescue is a popular grass for pastures due to the plant being drought and overgrazing-resistant. It grows well during the fall and is a perennial grass. It also provides a lot of nutrients for your horse. The problem for broodmares, though, comes from the fungus called endophyte that is produced by fescue.

    Endophyte Fungus

    • Though the fescue produces the endophyte fungus, you may not want to replant your pasture with endophyte-free fescue, as the endophyte-free fescue is not nearly as hardy. The reason for fescue's hardiness, and the problem it can cause to your broodmare's fetus, is from the alkaloid ergovaline that the fungus produces. According to Cornell University, the fungus is worst when the plants are developing seed heads.

    Toxicity Problems for Broodmares

    • There are many things that can happen as a result of the fescue toxicity. Mares can abort the foal, gestate for thirteen months or longer, develop a thickened placenta, have a difficult birth, retain the placenta after birth or not be able to produce enough milk for the foal. Cornell University states, "Nonpregnant horses can safely graze on endophye-infected fescue pastures, as can broodmares during the second trimester of pregnancy."

    Toxicity Problems for Foals

    • Foals born with fescue toxicity may be born too large and not have enough muscle mass, the hooves may be overgrown or they may have have hyperthyroidism, which, states Cornell University, causes "poor suckling reflex, lack of coordination and low body temperature." Also, these foals don't produce the same amounts of natural antibodies as normal foals do. As the foal develops, his teeth may erupt too soon or not in the usual order.

    Prevention and Treatment

    • The best way to avoid fescue toxicity is to prevent the mare from grazing on the pasture or to stop feeding fescue hay. Plant other grasses on the pasture to dilute the effects of the fescue, or you can feed hay that's not fescue.

      A pregnant mare that is grazing on fescue can be given drugs to reduce the toxicity. These include domperidone, perhenazine and reserpine.