"I was chairman of the committee for a few years and my forte was keeping everyone working together, understanding it but trying not to distort what needed to get done.
"There's been a whole lot of people and I've been a cog in the wheel for booting Tb out of Otago."
He had Tb in his herd in 1989, back when most people did not know possums were linked to the disease.
The disease was initially detected on his neighbour's farm, where 219 cattle were infected in a year.
Soon after, Tb was detected on the McNab farm and other neighbouring farms.
The disease was a serious animal health problem, which impacted heavily on-farm and if left unchecked could be a threat to the farming industry's international reputation.
When he got a phone call about a meeting where people were expressing concern about the possum problem, he put his hand up to volunteer.
At the age of 32 in 1989, he was the youngest member.
By the mid-1990s, bovine Tb had reached every corner of Otago and herd infections peaked at about 300.
The committee had support from the Animal Health Board, which was now Ospri.
"Their staff were passionate about the cause, and it was great to be involved."
A lot of hard work got results.
"It's been a great journey."
Farmers were more likely to listen to and follow other farmers because there were people who had infected herds and really understood the importance of knocking it back.
"We were able to get the following we needed to get a levy in place by the mid to late 1990s."
The key to the success of the journey was a lot of possum control - on the ground and 1080 aerial control, he said.
Farmers could Tb-test all they liked, but unless they got rid of the possums, they would reinfect the cattle.
"We also worked out quickly that if a property had Tb through infected possums, you didn't just need to control that property, you had to go to properties on either side.
"You were chasing your tail if you just did individual properties. You had to do areas."
The other keys to success were movement control, Tb testing and vector control.
If you got a reactor - an animal that tested positive for Tb - you could not move animals without having stringent controls about moving them.
"Once moved, you had to re-test again to make sure they hadn't gone through the test and not been detected."
Now he was "semi-retired", his oldest son Lyndon runs the farm.
"I think it's good I've passed the baton to my son.
"He's doing all the technology stuff that I'm not overly confident with. He walks around the farm with his phone and does all sorts of things, it's amazing. The technology makes that sort of process so much simpler and more accurate."
Technology had helped with having an accurate traceability system: a farmer could go into the system and access all their animals' information.
"In the early days, the ear tags were mostly recorded manually. People often got the number wrong and it wasn't anywhere near as effective as the electronic system."
It was important to try to register animals and record all their movements and be careful where stock was bought from.
"It's not only Tb, but we've also had M. bovis in New Zealand, and there could be something else."
When a generation got through a crisis, the knowledge gained tended to get lost over time unless the factors which led to that programme being developed were still in the background,
"That's certainly a concern of mine, but I'm trying to spread the word among the young ones and let them know about this."
