Late summer flush of dallisgrass can lead to ergot poisoning in cattle
10/2/2013 at 12:00 a.m.
From the University of Arkansas Division of Agriculture:
Grass seedheads that cattle find delicious could turn fatal if the seedheads are covered in ergot fungus, said John Jennings, professor of forages for the University of Arkansas Division of Agriculture.
Dallisgrass is very common in the southern half of the state and grows in low, moist soils. As a forage, it’s high quality and very palatable for most grazing livestock. The problem is the fungus, named Claviceps paspali and commonly called ergot, which infects the dallisgrass flowers. As the plant grows, the fungus replaces the seed. The fungus contains alkaloids that can affect the livestock’s nervous system.
“Ergot poisoning, also known as ‘dallisgrass staggers’ is a problem in late summer and early fall,” he said. “The rainy weather in August led to a flush of dallisgrass forage and the seedheads are commonly infected with ergot.”
Jennings said the most common scenario for ergot poisoning occurs when new cattle, not previously exposed to dallisgrass, are brought onto a farm and are turned into a field that is at the full seedhead stage. Cattle selectively graze seedheads and that can lead to a very high dosage of ergot alkaloids. Even on farms where cattle are previously exposed to dallisgrass, poisoning can occur when animals are hungry and are turned into a field full of seedheads. Symptoms are much less common in herds exposed to dallisgrass in mixed grass pastures.
“In the very early stages of the disease, the only sign seen may be trembling of various muscles after exercise,” Jennings said. “As the disease progresses, the animal becomes uncoordinated with continuous shaking of the limbs and nodding of the head.”
Eventually, a severely affected animal may stagger, walk sideways, or use a goose-stepping gait. Death can occur in severe cases.
“There is no cure for ergot poisoning, but removing cows from infected pastures when symptoms are first noticed usually results in uneventful recovery in three to five days,” he said. “Clipping seedheads to prevent animals from grazing them helps prevent the problem from occurring. Ergot toxicity from dallisgrass hay is very uncommon since the total intake of hay forage dilutes any ergot contained in the hay.”