The 3-year-old Saanen doe, owned by Margaret Tomes, faced stiff competition from the champion animals in the other livestock sections, including the beef cattle, equestrian, sheep, alpaca and boer goat entries.
Mrs Tomes was delighted with her doe's achievement, saying it was a huge thrill. It was good for dairy goats - "It just puts them out there" - and everyone was "very chuffed".
Mackenzie was the last show of the season for Mrs Tomes, who farms at Island Stream near Maheno with her partner Craig Batchelor.
She took four goats to Fairlie and "scooped the pool" in every class.
It has been a successful showing season for her goats, with Rosey now a grand champion which was "pretty good" for a young doe.
"They're usually 7 or 8 before they get to that stage," she said.
Mrs Tomes bred Rosey, who had always stood out in the herd.
Not only was she a very elegant doe, but she had an "absolutely superb" udder and milked about six litres.
Mrs Tomes aimed to breed a goat that was not only elegant, feminine and well put together, but one that produced plenty of milk.
Rosey was not a big doe and to yield six litres was "fabulous" at her age. Some of Mrs Tomes' goats milked up to 10 litres.
Mrs Tomes was first given a kid by a friend more than 20 years ago and dairy goats had become a passion for her.
She has about 100 goats. She has exported, as well as selling commercially.