COLLEGE STATION — Changing cattle diets now will stop illness from a poisonous fungus currently affecting several South Central Texas pastures, officials with Texas A&M University said.
Toxicology experts at the Texas Veterinary Medical Diagnostic Laboratory determined from grass samples — some of which had been ingested by animals that later died — that the fungus, ergot, is present on dallisgrass seed heads in some pastures.
Shredding off the seed heads, moving the cattle from the pastures, or providing cattle with an alternative such as hay bales until seed heads are removed, can stop the problem.
“The area that is being hit pretty hard right now is the triangular region from San Antonio to Houston to College Station,” said Dr. John Reagor, TVMDL head of diagnostic toxicology.
The problem arises when dallisgrass forms seed heads in pastures. Ergot grows on the seed usually after mid-summer rains. Reagor said droughty conditions impact the problem because cattle tend to turn to dallisgrass when dry conditions — such as those being experienced across Texas now — make bermuda grass less palatable. Cattle become sick after consuming a significant amount of ergot-infected dallisgrass.
Heavy ergot consumption causes nervous conditions seen as hyperexcitability, altered gait, muscle tremors and a lack of coordination in fast movements.
“Cattle might fall down, panic and not be able to get up,” Reagor said. He said the diagnostic lab, which has handled dozens of calls this week, knows of at least six cattle that have died as a result of eating ergot-infected dallisgrass.
The condition causes similar symptoms in cattle to those seen with LSD use in humans, according to Dr. Larry Boleman, Texas Agricultural Extension Service beef cattle specialist.
“Cattle show hallucinative symptoms and may fall down or stagger,” Boleman said. “The resulting hyperexcitability may cause the cattle to charge humans, but because of their lack of balance and staggers, they are not likely to get to you. What happens to the cattle after they eat it — staggering, falling down and such — is a manifes tation of the chemical changes in the body.”
Boleman and Reagor agreed that dallisgrass poisoning can be stopped by moving the cattle off the pasture, then shredding with raised shredder blades to remove the dallisgrass seed heads only, leaving as many leaves of the grass for the cattle to feed on when returned to the pasture. If moving cattle away from the source is not possible , cattle should be given a substitute feed source such as hay to eat while the seed heads are being clipped, Boleman said.
“Hopefully, the cattle will consume the alternative feed source instead of ingesting the dallisgrass seeds until the clipping is complete,” he said. “And if you know you have dallisgrass in your pasture, a preventative measure is to manage it by grazing it enough so that the seed head will never develop.”
Cattle that have ingested ergot-infected dallisgrass often recover if provided a safe diet.