DALLAS (AP) - The sun was setting when Jerry Abel's cattle began to bellow on his Central Texas ranch. They were convulsing by the time he rushed to the pasture. Within hours, Abel had lost almost all his herd.
The culprit: toxic grass.
Abel's 15 dead cattle represent the first documented case of cyanide deaths being linked to a common Bermuda grass hybrid found in grazing lands across the Southeast. Although the incident in late May initially sparked concern from other ranchers who use the same grass, state agriculture experts say they believe the problem is isolated and there's no cause for alarm.
"If cattle are already on pasture, don't worry about it," said Larry Redmon, a specialist with Texas A&M AgriLife Extension Service, which worked with state and federal agencies to investigate the deaths. "Chances are it's not going to be an issue." But, he said, "I would never say never."
Preliminary results from the investigation show Abel's Tifton 85 grass contained cyanide, or prussic acid, though Redmond said what caused the poison to build up remains unclear and under investigation.
The grass, a warm-weather perennial grown south of the Red River, was released to ranchers in 1992 for its drought resistance and nutritive value and is perhaps the most commonly used Bermuda grass variety in Texas, the nation's leading cattle state.
Since other grasses such as sorghums or Sudan can pose cyanide danger, most ranchers know to wait seven to 10 days after new growth before sending cattle to graze, Redmon said. That allows the grass time to release the cyanide into the atmosphere.
But because this is the first reported case of deadly levels of prussic acid in Bermuda grass, the 69-year-old Abel had no idea his cattle were in danger. He's been a rancher since 1977 and growing Tifton 85 on his pasture northeast of Austin for 15 years.
"I was totally, completely surprised," he said from his Elgin ranch, which contains about 30 acres of Tifton 85. "I never expected anything like this."
At about 8 or 9 in the evening on May 24, Abel let his 18 head of Corriente cattle into the pasture. His trainer heard the first bellows, and when they returned to the pasture, they saw many of the cattle convulsing, some already dead. Just three cattle survived.
Abel called his veterinarian, who came to the ranch the next morning to begin autopsies on the animals. The U.S. Department of Agriculture and Texas Department of Agriculture are working closely with the extension office on the investigation.
The extension service will attempt to recreate in a greenhouse all the factors that may have caused the prussic acid release, Redmon said.
He called the cyanide deaths a "perfect storm" of conditions that remain under investigation. The grass, which had been stressed by drought, soaked up spring rains that prompted lush growth. Prussic acid levels are highest in new growth, which is the layer eaten first by cattle. Grasshoppers, which had reportedly infested the area, may have damaged the grass tissue, causing a release of prussic acid. The cattle were eager to munch on fresh grass.
State and federal agriculture officials could not provide a tally of how many cattle die from eating toxic grass. Redmon said he has heard of other large numbers of cattle dying at once from lightning, nitrates or algae poisoning. Strange toxins also have been known to kill cattle in states such as Illinois and Nebraska, though experts and ranchers agree those kinds of deaths are rarer.
Redmon stressed that thousands of ranchers across the southeastern United States continue to graze their cattle on Tifton 85 and have reported no issues. He said ranchers expect about a 2 percent loss each year "as part of doing business."
A few ranchers have called Abel to get his advice, but he said he's pointed them to the extension service and its recommendations. Other area ranchers said they will do more research on the incident, but aren't concerned with their own fields.
Jim McAdams, former president of the National Cattlemen's Beef Association and long-time Texas rancher, said he always gets concerned when extreme weather causes rapid growth of hay or grass.
"Weird things happen," said McAdams, 62, who has about 40 acres of Tifton 85 near Huntsville. "It's just something that we ranchers have lived with for a long time."
Jim Russell, a grass grower and distributer in Sulphur Springs, questioned whether cyanide was the main culprit in the deaths of Abel's cattle.
"Anytime you put real hungry stomachs on a pasture you're going to have problems," said Russell, 74, who has been in the hay business since 1979 and isn't worried about his grasses. "Their bodies can't handle it."
Abel, who does not remember who he purchased the Tifton 85 sprigs from nearly 15 years ago, said the cattle were given hay and water in their pens before being turned out into the field. He added that anytime cattle are set loose to graze in a new pasture, even if they have been fed hay first, "they're going to go after it."
Abel said he has replaced the dead cattle and is keeping all his livestock in pens and feeding them hay. He said the Tifton 85 grass can still be used as hay because the prussic acid eventually dissipates.