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Livestock management to reduce ergot fungus intoxication this summer

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Cool, wet springs followed by hot early summers are the right climatic conditions for ergot fungus to grow in grass. Livestock grazing management practices can reduce the negative impact of the ergot fungus during the grazing months.

“Current weather conditions may lead to ergot problems for cattle and other livestock grazing grass this summer,” MU Extension Livestock Field Specialist Patrick Davis said.

This fungus, Claviceps purpurea, produces compounds called ergot alkaloids, which act similarly to those found in endophyte tall fescue grass and are toxic to livestock, if consumed in excess.  

“Ingestion of ergot alkaloids produced from the ergot fungus negatively impacts animal performance by vasoconstriction of small arteries,” Davis said.  

The vasoconstriction results in reduced blood flow to extremities, leading to the loss of tips of ears and tails, as well as a rough hair coat. 

High levels of ergot alkaloid-induced restricted blood flow can also cause lameness, similar to what is seen with “fescue foot” during the winter months, along with joint swelling and sloughing of hooves.  

Blood flow reduction also decreases the animal’s ability to dissipate heat, which can result in heat stress, weight loss, and extended periods of time in water or shade.  

Davis urges livestock operations to be aware of these symptoms and if they arise remove animals immediately from the pasture and forages to help prevent further problems.

“Monitor pastures or hay regularly to determine if the fungus has infected any grasses, as evidenced by the presence of ergot sclerotia, which are also referred to as ergot bodies,” Davis said.  

The fungus produces a sclerotia, which replaces the plant ovary tissue and seed head, appearing as dark brown, purple or black bodies, sometimes described as resembling rodent droppings.  

These sclerotia typically show up in grasses such as brome, timothy, tall fescue, even that which is already infected with toxic endophyte, and orchardgrass. Since there is no practical way to eliminate the ergot producing fungus from the pastures, Davis urges careful inspection of fields annually to determine the presence and severity of the ergot infection, which helps in planning to reduce the negative impact on livestock during the summer grazing season. 

“Grazing or clipping pastures to reduce animal consumption of ergot-infected seed heads is a practical way to reduce the incidence of ergot intoxication or ergotism in your livestock operation,” Davis said. 

In addition, this management strategy helps keep the pastures more vegetative which helps provide better quality forage for consumption and better animal performance.  

Davis urges cattle operations and other livestock producers to manage pastures to reduce ergot consumption and the risk of intoxication, as well as provide better quality grass for improved performance of grazing livestock.

“Making ergotized grasses into hay is another way to remove a significant portion of the mature ergot bodies from infected grasses,” Davis said. 

However, Davis urges close inspection, testing this hay for the major ergot alkaloids and adjusting consumption in order to reduce the negative impacts on livestock during feeding. 

For more information on livestock pasture management to reduce livestock health issues related to ergotism, contact a local MU Extension livestock field specialist.  

To learn how to improve grasslands, go to extension.missouri.edu/programs/nrcs-mu-grasslands-project.

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