Earlier Pasture Growth in 2012: Implications for Tall Fescue

In Kentucky and surrounding states, winter has been abnormally mild. Thus, most cool season pasture grasses have not had a real dormancy period. Unless there is a late cold spell, we expect pastures to "green-up" earlier this year.

This should benefit owners whose horses can start grazing greener pastures earlier in the year; however, it might cause problems for owners grazing pregnant mares on pastures containing tall fescue. Normally, fescue toxicity is not a concern in Kentucky between mid-December and the end of March or early April because ergovaline (an alkaloid produced by a fungus that lives inside the plant) is low during the winter. With earlier green-up likely, pregnant mares could begin showing clinical signs of fescue toxicity (e.g., prolonged gestation; absence of milk production; foal and mare mortality; tough, thickened, or retained placentas; weak and immature foals; reduced serum prolactin levels; and reduced progesterone levels) as early as March. Therefore, exercise extra caution before turning out pregnant mares on pastures containing fescue.

Ray Smith, PhD, a professor and forage extension specialist at the University of Kentucky, provided this information.

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Disclaimer: Seek the advice of a qualified veterinarian before proceeding with any diagnosis, treatment, or therapy.