Tall fescue is an important grass for feeding livestock, and it grows very easily in Kentucky pastures.

However, the super grass does come with its own problems — namely, a common endophyte, a fungus that can be toxic to the animals grazing it.

Some of the earliest research about fescue came out of the University of Kentucky. For decades, now, research in the College of Agriculture and many other institutions has focused on fescue toxicity.

Most recently, scientists in the departments of Animal and Food Sciences and Plant and Soil Sciences have teamed up with the U.S. Department of Agriculture’s Agricultural Research Servicet o find ways to minimize fescue toxicity.

“The loss of productivity in animals grazing endophyte-infected tall fescue results in more than $600 million lost in the beef industry alone,” said Professor David Harmon, an animal scientist who studies ruminant nutrition.

“Animals consuming the infected grass show reductions in feed intake and weight gain, which can be exacerbated in times of heat stress like we saw this past summer. We are grateful to work with the ARS lab because they bring expertise we don’t have. We benefit from one another; it’s a win-win to have them here.”

Harmon recently worked with Kyle McLeod, associate professor in Animal and Food Sciences, and Jimmy Klotz, a scientist with the USDA Agricultural Research Service, housed on the UK campus.

They used steers at UK’s C. Oran Little Research Center in Woodford County and administered either infected or endophyte-free fescue seed directly into their rumen to examine the effects.

“The study data simply told us that the steers given the endophyte showed a reduction in their basal metabolic rate (the energy animals expend daily while at rest),” McLeod said. 

Despite that, the researchers were surprised to find that some animals that consumed endophyte-infected fescue performed poorly, while others showed no difference from the control group that were given the endophyte-free fescue. 

All three scientists agreed the results indicated more research is needed to determine the origin of the response — why the steers’ metabolic rates decreased.

Harmon said the team is following up their research with a second study to evaluate how efficiently the steers use the feed.

He said it’s just one facet of a complex syndrome. 

“The benefit (of the research) is that we are making progress towards understanding the effects of the endophyte on the animal,” McLeod said, “so perhaps we may one day eliminate the negative impact.”