One of Australia's biggest bovines has set aside embarrassment and made a bowel movement for a good cause.

Big Moo is thought to be the largest cow in Australia, standing at 186 centimetres and weighing 1.5 tonnes.

Almost 100 people bought stakes in Big Moo's paddock at Glencoe in SA's South East to test their faecal fortune — the winner was the lucky punter who bought the square patch where the eventual drop landed.

Owner Joanne Vine said she came up with the idea of a cow pat lottery when she was younger and decided to make the idea a reality with her celebrated steer.

"I think I read about it in a book in my childhood and I'm not sure how it came to mind for this particular event," Ms Vine said.

"I was musing [about] how I could raise money with Moo and this popped out of my memory."

The winning pats were dropped after three hours. ( ABC South East: Jemima Burt )

In the end, spectators had to wait just over three hours for the final evacuation to take place, with local Emma Kennon donating her $100 winnings to charity.

All funds raised from the day went to the Mount Gambier branch of Riding for the Disabled, an organisation that gives people with a disability the chance to learn to ride and care for horses.

Charity spokeswoman Megan Wilkinson said almost $1,000 was raised from the event, which would make a huge difference to the work of the volunteer-run organisation.

"We're completely run by volunteers and donations really help us with horse care and maintenance around the place," she said.

A cake replica of Big Moo. ( ABC South East: Jemima Burt )

While waiting for a cow to have a bowel movement is not quite the typical way to mark Australia Day, Ms Vine said she thought the event fit in well with the spirit of the occasion.

"This is so Australia Day — the idea that a woman could mark out lines on a paddock to get her big cow to do poos in it," she said.

Despite towering above his paddock-mates, Ms Vine said the animal was a gentle giant.

Originally destined for the freezer, Big Moo's calm nature and unusual size made him part of the family.

A toddler gets an up-close look at giant steer Big Moo. ( ABC South East: Jemima Burt )

Ms Vine said his fondness for the camera also made him tourism attraction in the small farming town of Glencoe.

"He loves cameras. If he sees a camera, he smiles," Ms Vine said.

"I'm not sure if he knows he's famous. He knows every little while a mass of people turn up and pat him all over and give him scratches and then go away again."