Farmers in the US breathed a sigh of relief over the country’s mad cow scare after veterinarians said the single animal in question was “not mad, just kinda silly”.

An Iowa beef rancher called authorities after one of his cattle began playing practical jokes on the rest of the herd and performing zany antics.

“Myrtle was doing things like licking the electric fence and just taking the shock without showing it, so that other cattle would do the same and get a jolt,” said the owner, Randy Krause.

“She was squirting other cattle with milk from her udder, and there was a lot of physical comedy like pratfalls and putting on Monty Python-style silly walks. Things like that.

“Her George W Bush impression was really clever but some of the fart jokes were a bit off-colour. Although she really knew how to milk the audience for laughs and get them rolling in the hay.”

Myrtle would also periodically veer into a deep funk, becoming reclusive and writing darkly tinged satirical poetry. Fearing manic depression, a condition that has afflicted so many of the world’s great artists and comic talents, the farmer called his vet.

Unfortunately for the Red Angus breeder cow she was sent for a lobotomy so scientists could test her brain matter for mad cow.

Animal rights group People for the Ethical Treatment of Animals said the procedure was not only cruel, it had brought a premature end to a promising career in stand-up.

“She was ahead of her time in comedy,” said PETA spokeswoman Snowchild Moonbeam.

“It’s not Myrtle’s fault that the world was not ready for her unique brand of bovine humour. Her jokes worked on a number of levels.”