A major part of his life had been dedicated to breeding a better Holstein Friesian cow since he and his wife, Judy, began sharemilking on his family farm "The Gums" on the Taieri.
The Aitkens launched the Broomfield stud after buying 17 registered cows in 1973.
"You always want to breed one that is better than the last one," Mr Aitken said.
He was presented a Holstein Friesian New Zealand Otago branch life membership at a surprise ceremony earlier this month, an honour which "blindsided him".
"It has been one hell of a ride and I hope it is not the finish."
A recent battle with cancer and a major eye operation had not limited his ability to spot a good cow.
He pointed out some of his favourite cows on a herd walk in Momona before the ceremony, his admiration ranging from "That’s as good an udder as you’d see anywhere around the world" to "look at how deep her body is — a big engine room".
At the ceremony, branch member Judith Ray, of Clydevale, listed some of Mr Aitken’s industry involvement.
"His contribution to our local branch and the wider dairy farmers of Otago has been huge," Mrs Ray said.
Mr Aitken had been the Otago branch chairman three times between 1979 and 1999 and was a driving force on the committees organising four branch conferences between 1985 and 2017.
Whenever the branch needed money to hold an event, he organised fundraisers, including bobby calf and cull cow donations.
He had held several roles within Holstein Friesian New Zealand, including classifier, director, judge, patron and president.
The life membership ceremony followed a herd walk the branch was hosting on the stud Airdrie Holsteins run by Mr Aitken’s son and daughter-in-law, James and Celia Aitken, in Momona, near Dunedin Airport.
After managing nightclubs on the Gold Coast, James returned home to the Taieri in 2009, age 32, a decade after moving to Australia.
"Ten years on the Gold Coast goes pretty quick and I thought I’d better get home and give milking cows a go," James said.
Returning home, he worked for Nathan Bayne, of Busybrook Holsteins.
James and his wife bought their about 90ha farm The Poplars in Momona and launched Airdrie Holsteins in 2011.
They established a herd by obtaining cows and heifers from 13 farms across New Zealand.
They now milk about 240 cows, about 80% Holstein Friesian, 15% Crossbred and 5% Red Holsteins.
Their breeding objectives include producing a cow which was not too big but able to produce milk, including robust udders.
James said he bought semen from several genetics companies for his breeding programme.
"I buy far too much semen — I can’t help myself."
He had hundreds of semen straws in his bank and he always vowed to use it rather than buy new genetics "but I always find something that looks interesting".
Sexed semen had been providing good results.
The only heifers he had artificially inseminated were the best six in the herd.
For the first time, he had a bull selected for the LIC sire-proven team and its semen would be available next year.
"Keep an eye out for him."
He had 10 embryos implanted in his herd last season and it produced three calves.
"One died and I got a bull and a heifer."
Implanting embryos and getting them to hold could be "quite hit-and-miss", but worth the effort for a good heifer.
"You only need one to make a difference."
His herd produced about 490kg of milksolids per cow last season.
A new in-shed feeding system was installed this past winter and had potential to boost production up to nearly 600kg of milksolids per cow this season.
He needs to increase production by 10% to cover the cost of the system but it needed to rise by 20% to make the effort worthwhile, he said.
The feed system cost about $70,000, including the silo and installation.
He had invested in $120,000 of meal to feed in the shed this season.
"So you have got to get a return on it."
"They are on target."
In a 22-aside herringbone shed, each day each cow gets served more than 4kg of meal — a mix of dried distillers grains, palm kernel, crushed barley, molasses and organic minerals.
"We’ve had three cows with mastitis this year and a couple of lame ones, which is incredible considering the crappy spring we’ve had and we are putting that down to the better minerals in the meal."
The in-shed feeding system would allow him to increase herd numbers.
He had hoped to increase herd numbers this season by some in-calf cows, which had been grazing kale, but they had slipped their pregnancy.
Vets were stumped for a reason for the miscarriages.
"It has never been a problem before. The same sort of cows have eaten the same sort of kale. It is frustrating as an average cow now is about $3000, so for them not to be in-calf and not be milking is a bit of a hit."
The Aitken family has two Holstein-Friesian studs. His brother, Andrew, runs Broomfield on The Gums in Maungatua, where he milks about 500 cows.
Denis said even though he wrote retired on his Customs form, his continued involvement includes mentoring people progressing in the dairy industry.
"I have about three under my wing."
Farm ownership was still attainable in the dairy industry without any family assistance, if someone had a plan and involved mentors with industry knowledge and business nouse.
"It just takes commitment."
