Fescue Toxicosis and Pregnant Mares

Fescue is a type of grass that is commonly used for lawns, pastures, and sports fields. It is a cool-season grass that is known for its ability to tolerate a wide range of growing conditions, including drought and shade. There are several species of fescue grass, including tall fescue, fine fescue, and creeping red fescue. Each species has its own unique characteristics, but they are all generally considered to be low-maintenance, durable, and attractive.

Fescue grass can become infected with an endophyte fungus through seed transmission. The endophyte fungus is a naturally occurring organism that lives within the fescue plant without causing any visible symptoms of disease. The fungus is transmitted from one generation of fescue to the next through the seeds of the plant. The endophyte fungus provides a number of benefits to the fescue plant, including increased tolerance to drought, heat, and pests. However, some strains of the fungus can also produce toxins that can be harmful to grazing animals such as cattle and horses, causing a condition called “fescue toxicosis”.

While fescue grass itself is not harmful to pregnant horses, the endophyte fungus that can grow on it can be toxic. Pregnant horses should avoid fescue grass that has been infected with endophyte fungus. The fungus produces chemicals that can cause prolonged gestation, dystocia (difficulty giving birth), decreased milk production, and even abortion in pregnant mares.

To avoid fescue toxicosis, it is important to feed pregnant horses hay and pasture that is free of endophyte fungus. If you are unsure whether the fescue grass in your area is infected with endophyte fungus, it is best to consult with your veterinarian for guidance on the safest diet for your pregnant mare.

It can be difficult to tell if your fescue grass is infected with endophyte fungus just by looking at it, as the fungus often does not cause any visible symptoms of disease. However, there are some signs in the live plant that can indicate the presence of the fungus, as well as the potential for fescue toxicosis in grazing animals. To determine whether your fescue grass is infected with endophyte fungus and whether it poses a risk to grazing animals, you can have the grass tested for the presence of toxins. Testing can be done by a laboratory that specializes in forage analysis.