The Good

When farm owners find themselves with more pasture than they need, mowing it down doesn’t have to be the only management option. Allowing pastures to grow to full maturity (seedhead stage) and then harvesting them can produce quality bedding for stalls or run-in sheds. This material is simply overmature or low-quality hay because it is allowed to grow beyond the normal harvest window for hay production.

Many farms that use this practice report reduced incidences of colic because the horses will consume the bedding after they run out of hay in the stall, thus mimicking continuous grazing. And by harvesting pastures farms are able to grow their own bedding at a fraction of the cost of purchasing straw or shavings.

The Bad

Bedding harvested from pastures in the Southeastern, South-central, and Northwestern United States is likely to contain tall fescue. Tall fescue can be infected with a fungal endophyte (Neotyphodium coenophialum) that can produce ergot alkaloids, some of which are harmful to pregnant mares.

Tall fescue can be infected with a fungal endophyte that can produce ergot alkaloids, some of which are harmful to pregnant mares.

Ergovaline, the most common ergot alkaloid found in infected tall fescue, varies in concentration throughout the year depending on weather conditions and pasture management. It also varies within the plant. Infected tall fescue's stems and seedheads often contain higher levels of ergovaline than the leafy part of the plant, meaning ergovaline levels will be high when pastures are harvested at full maturity, as they are for bedding.

However, ergovaline is sensitive to light and heat, and levels will often drop in bedding material during the drying process. Research results and case studies have found exceptions, though, when ergovaline concentrations have remained high even after baling. For this reason, have bedding (or hay) containing infected tall fescue tested for ergovaline concentration before being used for broodmares.

The Ugly

Many grasses can also be infected with the fungus Claviceps sp. Unlike the better-known tall fescue endophyte, this fungus is identifiable in plants by the appearance of dark purple or black kernels on the seedhead called ergot bodies. While these two fungi are not related, they both produce ergot alkaloids that can be harmful to broodmares.

Claviceps sp. are common in cereal grains such as cereal rye and barley but can also be found on grass seedheads such as ryegrass and occasionally tall fescue. These alkaloids are not distributed throughout the infected plant, but instead are contained in the ergot body, which can complicate testing. Alkaloid concentrations in these bodies can be significantly higher than what is found in tall fescue and, therefore, quite dangerous to horses.

Growing Safe Bedding

Given these challenges, the easiest solution is to avoid using grass bedding for pregnant mares. However, you can implement some simple management changes that can reduce the risk of complications and allow you to still utilize this cost-saving practice even among broodmares.

1. Know if your pasture contains tall fescue Tall fescue is a bunch-type grass, dark green in color with serrated leaf edges and prominent veins. If a pasture contains more than 10% tall fescue, it should be tested for endophyte infection levels every year. While infection rates will not vary greatly from year to year, increases are common and should be monitored. Contact your local county extension agent for help with identification and testing or see "Forage Identification and Use Guide" at uky.edu/ag/forage/foragepublications.
2. Test infected bedding If you produce bedding (or hay) from endophyte-infected tall fescue pastures, test this material before using it for broodmares. You can still use high-testing lots for growing horses or barren mares and save the safer material for broodmares.
3. Inspect pastures for ergot bodies in late spring Testing can detect ergot bodies in your pasture. Accuracy of the results depends on whether the small sample taken for testing actually included ergot bodies. The best time to detect ergot bodies in the pasture is before harvest. Once seedheads are visible, take a moment to walk through pastures and inspect them for ergot bodies. If you find them, do not use this material with pregnant mares.

A variety of laboratories across the country offer tall fescue testing. A few are listed below. Endophyte tests will look for the presence of the fungal endophyte that produces ergot alkaloids. Ergovaline tests will quantify the amount of ergovaline in the material.

Agrinostics Ltd. Co.

P.O. Box 882

Watkinsville, GA 30677

www.agrinostics.com

Iowa State University Veterinary Diagnostic Laboratory

1600 South 16th

Ames, IA 50011

www.vetmed.iastate.edu/diagnostic-lab

Oregon State University Endophyte Service Laboratory

139 Oak Creek Building

Corvallis, OR 97331

www.oregonstate.edu/endophyte-lab

University of Kentucky Regulatory Services

103 Regulatory Services Building

Lexington, KY 40546-0275

www.uky.edu/ag/regulatoryservices

University of Kentucky Veterinary Diagnostic Laboratory

1490 Bull Lea Rd.

Lexington, KY 40511

www.vdl.uky.edu

University of Missouri Veterinary Medical Diagnostic Laboratory

P.O. Box 6023

Columbia, MO 65205-6023

www.vmdl.missouri.edu

Managing and monitoring pastures properly can result in the safe production of quality hay or bedding for all classes of livestock.

Krista Lea, MS, and Ray Smith, PhD, professor and forage extension specialist, both within the University of Kentucky Department of Plant and Soil Sciences, provided this information.

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