A €10,000 reward is being offered in Germany for the safe return of a cow called Yvonne who went on the run in May after apparently sensing she was about to be sent to the slaughterhouse.

Yvonne, a six-year-old dairy cow, has, in the words of one newspaper, become "a kind of freedom fighter for the animal loving German republic" since she escaped from her field in the village of Zangberg, 50 miles north-east of Munich, on 24 May.

Having been fattened up, she was due to be dispatched when she managed to breach the electric fence surrounding her farm. For months she led a quiet life grazing among the fir trees of nearby forests, until she nearly came a cropper crossing a road into the path of a passing police car.

As word spread of this invincible cow, animal protection activists got involved, incensed that local hunters had been given permission to shoot Yvonne on sight. Gut Aiderbichl, an animal sanctuary over the Austrian border in Salzburg, agreed to buy Yvonne from the farm for €600 and has offered her a paddock with grass to graze on for the rest of her days.

Now a fight is on as the bovine protectionists are pitted against the trigger-happy Bavarians, who shot and killed Bruno, the first bear to be seen on German soil for 170 years, in June 2006.

Gut Aiderbichl are pulling out all the stops to catch Yvonne alive. Last week they enlisted the help of a bull called Ernst to try to lure her back home. Ernst has "a deep baritone moo that will appeal to Yvonne", as well as a particularly manly musk, said the sanctuary's founder, Michael Aufhauser. "He is the George Clooney of bulls." Sex is not on the agenda, however, as Ernst is castrated.

Aufhauser also called on an animal psychic to communicate with Yvonne from afar. Franziska Matti, an animal communication expert from Berne in Switzerland, said she had managed to contact Yvonne using telepathy. "I spoke to her yesterday and she said that she was fine but didn't feel ready to come out of hiding," said Matti. "She said she knew that Ernst had been waiting for her but that she was scared. She said she thought that humans would lock her up and she would no longer be free."

Since the German tabloid Bild offered a €10,000 reward for Yvonne's safe capture on Saturday, the race to find her has heated up. In Monday's Bild an 11-year-old boy called Sepp claimed to have discovered a fresh hoof print from Yvonne in the woods near his home. The boy had been tipped off by his grandmother, he said, who had spotted a cow while out collecting mushrooms two days previously. "I know that I will find her. My dad has 18 cows. I often have to help him feed them and take them out to pasture. I know what I'm doing," he told Bild.

On Monday Aufhauser said he had leased a helicopter to track down Yvonne. If that did not work, he had a secret weapon: Yvonne's two-year-old son, Friesi, who was previously believed dead but turned up alive at a local farm. Friesi was offered by his owner to Aufhauser, and was on Monday undergoing "intensive training" to learn how best to call to his mother. "We know that the bond between mother cows and their sons is very strong. She will not be able to ignore him," said Aufhauser.

Franz Märkl, mayor of Zangberg, said he was delighted Yvonne had decided to go missing during the traditional summer news lull known in Britain as "silly season" and in Germany as "Sauregurkenzeit" – literally "sour cucumber time", a reference to the days when good vegetables are scarce.

"We trained the cow well for the summer [news] vacuum," Märkl told the Süddeutsche Zeitung. "Now everyone in Germany has heard of our lovely village."