Pasture-Monitoring Results Released by UK Researchers

The 2002 pasture-monitoring program for mare reproductive loss syndrome produced key information about Kentucky's pastures, but tests will continue in 2003 as a definitive cause for the syndrome is sought.

From Feb. 21 to June 28, 2002, personnel from the University of Kentucky collected more than 3,000 samples from 12 Central Kentucky horse farms and one hay farm. Analysis of those samples and corresponding data found significant correlations between cases of MRLS and the presence of black cherry trees in proximity to pasture.

However, there was also an indication that tall fescue alkaloids could account for some late-term abortions on farms where Eastern tent caterpillars or cherry trees were not visibly present.

Dr. Jimmy Henning, extension forage specialist at UK, said there are some "real positive things" contained in the report, most importantly that "we know a lot more about what is normal" in Kentucky pastures. "For example, we know we can have cyanide in white clover, but it's not that much, and it's not a real problem. We know the mineral content (of forages) during weather changes."

One of the things agronomists learned is that grasses normally found in Kentucky are not changed that much by weather, and that horse managers have done a good job managing pastures. So, while the weather may have an indirect effect on MRLS, it's more coincidental due to the presence of Eastern tent caterpillars in pastures than the weather itself.

Mycotoxins still have some people bothered, Henning said, but when mycotoxins were found, the levels were low.

On the topic of fescue and endophyte infection, Henning said: "Not surprisingly, tall fescue can have high endophyte levels in pastures certain times of the year. Perhaps that tells farm managers to pay a little more attention to tall fescue. Test it to see if it's infested. Treat late-term mares with Domperidone."

Henning said the UK agronomists and entomologists are tracking caterpillar egg masses this winter to try and predict the caterpillar population in 2003. He said some of the monitoring of pastures next year will be correlated with the stages of the caterpillar's growth.

When asked about any correlation with pastures and the reproductive losses in the fall of 2002, Henning said while researchers at the University of Kentucky are treating this as a "deadly serious" problem, no one has shown him a correlation with MRLS to this point.

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