Texas animal scientists said a type of grass known as "Tifton 85" bermuda grass is to blame for the poisoning of 15 head of cattle on an 80-acre ranch east of Austin. The animals went into convulsions and were dead within hours of being released into the pasture to graze. Only three cattle in that small herd survived.

"It's a bermuda grass that nobody ever thought of as potentially having this problem," said Gary Warner, a cattle veterinarian in Elgin, Texas, who autopsied the animals.

"We don't know probably all we need to know currently. We do know the cattle died from prussic acid poisoning and we know the grass tested positive for prussic acid," said Warner. "It is the same as cyanide poisoning, the same as they used in the gas chambers in Germany."

Warner said drought conditions likely helped pre-dispose the field to this event. The grass in question was heavily fertilized with nitrogen but was not balanced with other needed compounds, which could have contributed to the development of the toxic grass, he said.

Because the Tifton 85 is planted broadly across Texas, agricultural officials around the state are scrambling to investigate the causes and what can be done to avoid more deaths. Other fields have reportedly tested positive for the poison, but no other cattle have died.

Larry Redmon, a state forage specialist with Texas A&M University, said in a blog posting that the situation was considered unprecedented.

The hybrid Tifton 85 bermuda grass was introduced by government plant breeders in 1992 and no problems like this have been reported before, scientists said.

In a separate incident in western Kansas, several calves on a drought-stricken ranch also succumbed suddenly to what investigators have determined to be liver toxicity.

Gregg Hanzlicek, director of Investigation Unit with the Veterinary Diagnostic Laboratory at Kansas State University, said Tuesday that investigators were blaming a Senecio species of weed that causes acute-to-chronic liver toxicity.

Cattle normally will avoid dangerous weeds, but drought had destroyed much of the normal grass in the area, said Hanzlicek.

"We to my knowledge have not seen this before. It is a really rare thing," he said.

(Reporting By Carey Gillam; Editing by Greg McCune and Philip Barbara)

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