His cousins Paddy (Turangi) and Johnson (Rotorua) also come from strong rodeo families.
In November the three will compete alongside the world's best at the inaugural Professional Bull Riders event in Christchurch.
They were recently named in a five-strong New Zealand team.
Mervyn said Professional Bull Riders events were based out of the United States and were recognised as the highest level of bull riding on the planet.
"This is a huge event and I am really excited to be competing on home ground alongside some of the best international riders out there at the moment," he said.
"I did not think they would ever have a [Professional Bull Riders event] in New Zealand.
"I thought we would always have to go overseas to do them."
The big event would bring together the top 22 cowboys from the United States, Australia and New Zealand.
Mervyn said he would love to do well at the competition and he had two main goals in the sport.
"I want to win the New Zealand title and win a world title even," he said.
Last season he finished just behind his cousin Davis in the race for the New Zealand title.
Mervyn has been competing in rodeo - from riding calves up to 1000kg bulls - for 13 years now and has never had a serious injury.
"I never have, touch wood.
"I've been stood on and bruised up but no bad injuries."
He said what made the sport addictive for a lot of people was the adrenalin rush.
"I still get a bit nervous before a big event but it is second nature to me now. There is an adrenalin rush every time you get on a bull."
He said the sport was not for the faint hearted and the best riders showed grit and determination.
"You have to have a big heart, never quit and you need to be tough. "
Mervyn and Davis are currently doing fencing around the area and trying to stay fit during the off-season.
Meanwhile, Paddy is competing in rodeo events overseas.