Freezing Cows Die From Fescue Foot

“Replacing toxic fescue with a novel-endophyte variety has huge economic benefit. It does require a season-long process to kill the old variety and reseed to new fescue.”

Craig Roberts University of Missouri Extension forage specialist

COLUMBIA — Reports of “fescue foot” causing loss of cows are coming in, says Craig Roberts, University of Missouri Extension forage specialist.

In severe cold weather, cows eating toxic fescue, a widely used pasture grass, suffer frozen feet with lost hooves. In one case a Missouri producer lost five cows out of a herd of 30. Other cases, less severe, are being reported.

An alkaloid from a fungus growing inside the plants of Kentucky 31 tall fescue causes losses. Once a foot is frozen, leaving a bloody stump, the cow cannot be cured.

“We’ve known prevention for 15 years,” Roberts says. “There are ways to reduce the problem but only one preventive: Replace toxic fescue with a new variety.”

The Alliance for Grassland Renewal works to teach farmers how to renovate old pastures and plant one of several new grasses known as “novel-endophyte fescue.”

The alkaloid in the old endophyte fungus causes blood vessels to contract. In winter this vasoconstrictor shuts blood flow to body extremities. Feet, tails and ears can freeze.

A cow can survive a lost tail switch, but she can’t walk to graze with frozen feet, Roberts says. Crippled cows must be put down.

Low blood flow in summer causes heat stress. This isn’t fatal, but it causes unseen economic losses. Cows in heat stress quit grazing and head to shade or to ponds to cool off.

Animals that stop grazing stop gaining weight. That loss cuts farm income when calves are sold.

“Losing a cow is losing the calf factory,” Roberts says. “This is serious.”

Fescue foot was first reported 75 years ago. It took until 1977 to discover the cause, an endophyte fungus. That threadlike growth lives between plant cells in the grass.

It’s a symbiotic relationship. The endophyte protects fescue from insects, diseases, drought and overgrazing.

Other naturally occurring endophytes give protection but don’t have the vasoconstrictor alkaloid.

“Replacing toxic fescue with a novel-endophyte variety has huge economic benefit,” Roberts says. “It does require a season-long process to kill the old variety and reseed to new fescue.”

Fescue foot has an economic loss. But losing a cow has an emotional impact as well. The loss is personal.

Other losses are mostly unseen, Roberts says. Abortions of early pregnancies are almost never seen. That doesn’t have the same impact on producers.

Fescue foot is third or fourth down the list of losses, Roberts said. Loss of unborn calves brings bigger dollar losses. Alkaloid also lowers daily gains. That cuts weaning weights. “It’s a big loss on payday,” he says.

Fescue foot cases dropped in recent warmer winters. However, other losses continue in all seasons.

“We know how to prevent losses, estimated at $900 million a year,” Roberts says. “Producers solve problems and increase profits by planting novel-endophyte fescue.”

Roberts warns that seeding an endophyte-free fescue doesn’t work. “We tried that in Missouri,” Roberts says. “Fescue needs endophyte protection to survive much past one year.”