Police have urged farmers and rural workers to take care when riding quad bikes, after a farm worker crashed his machine on a Georgetown farm on Thursday.
The worker was flown by helicopter to Dunedin Hospital with serious head and pelvis injuries after his quad bike rolled on him.
Constable Craig Bennett, from Kurow, said the man had not been wearing a helmet.
"Basically, he was moving cattle beasts and the right rear tyre clipped a cattle beast."
Const Bennett said the tyre continued to ride up the cattle beast, causing the 750cc quad bike to flip and roll right over the top of its rider.
The man was knocked unconscious and could have been lying prone for about 20 minutes before being discovered.
The 53-year-old man fractured his pelvis in the accident and will be immobilised for four weeks in the hospital after having his pelvis reset.
The incident had resulted in a "worrying time" for the man's family and it was an opportune time to remind rural residents to wear helmets when riding quad bikes, and to be aware of what the vehicles could do, he said.
"These machines are made to continue going, no matter what angle."
Quad bikes were involved in the deaths of four people in New Zealand last year, and more than 100 fatalities since 2000.
The Department of Labour last year produced a set of quad-bike guidelines to clarify the responsibilities of employers under the Health and Safety in Employment Act 1992.
The guidelines recommend wearing a helmet at all times, and using a motorbike, rather than a quad bike, for mustering roles on farms.
However, Federated Farmers North Otago high country section chairman Simon Williamson said the idea of replacing quad bikes with motorbikes was "ridiculous".
"Quad bikes are used on every farm in New Zealand. The reason there is so many accidents is because there is so many thousands of them out there.
"I think it's easy to point the finger and say it is a big problem but if you look at the thousands and thousands of kilometres every day done in this country for the amount of crashes, you have to put it in proportion a little bit.
"It comes down to common sense, you have got to know your machine and know its capabilities.
"I still think it's a good idea, especially on hill country if you have got some sort of bar on the back of it to stop it rolling over."
He said the use of a roll bar was a personal preference, and he acknowledged that not everyone believed that they worked.
