Fescue Sample Handling, Storage can Affect Analysis Results

Fescue Sample Handling, Storage can Affect Analysis Results

Much of Kentucky’s pastures contain fescue, and while those pastures can appear lush and beautiful, they can also be dangerous for the animals that graze them.

Photo: Courtesy Krista Lea, MS

Much of Kentucky’s pastures contain fescue, and while those pastures can appear lush and beautiful, they can also be dangerous for the animals that graze them. There is a fungus that co-exists with the fescue that produces compounds called ergot alkaloids that affect grazing animals' physiology. One of the most studied of the ergot alkaloids is ergovaline.

Ergovaline is blamed for a wide range of issues in pregnant mares, including prolonged gestation, difficulty foaling, agalactia (no milk production), and mare and foal deaths. Pastures are routinely tested to evaluate ergovaline levels.

Researchers at the University of Kentucky (UK) and the UK Veterinary Diagnostic Laboratory (UKVDL) found that sample handling and storage methods affected ergovaline concentrations in tall fescue samples. Because property owners make costly decisions based on ergovaline analysis, it is important that analysis results be accurate.

In their study, the UK researchers subjected tall fescue samples to a variety of transportation and storage conditions to simulate actual situations horse owners and managers might face. Transportation conditions included in a cooler on ice or under ultraviolet (UV) lights to simulate the dashboard of a vehicle. Storage conditions included ambient temperature, refrigerator, and freezer storage for one to 28 days. They measured ergovaline concentrations using standard laboratory methods.

The team found that no ergovaline was lost when samples were transported in a cooler on ice (for two hours or less); however, a significant fraction was lost when samples were subjected to light and heat (like on the dashboard of a vehicle). Also, ergovaline was stable in the freezer for 28 days; however, some ergovaline was lost in the first 24 hours in the freezer. Ergovaline was not stable in refrigerator or at ambient temperature, and those conditions resulted in significant changes in concentration during storage.

Managers and owners who are interested in sampling their pastures for ergovaline should store the samples in a cooler on ice for no more than two hours and transport those samples to the laboratory immediately. Alternately, they should be stored in a freezer until they can be transported.

For more information on tall fescue or ergovaline sampling, please contact your local county extension agent or visit uky.edu/Ag/Forage/ForagePublications.htm#Tall%20Fescue.

Krista (Cotten) Lea is a graduate student in UK’s Department of Plant and Soil Sciences.


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