"He was held on the ground by it and kicked and headbutted by it on the ground, basically," Mr Clarke said.
The man said he would have been more seriously injured if his wife had not been there to distract the cow while he was "getting dealt to".
"He was pretty shaken up. He'd been farming for 40-odd years and never had an experience like it in his life. Definitely a freak incident according to him."
Mr Clarke said even though the helicopter tended to scare offending animals away, he still had a good look around before getting out to attend to the man.
The cow had run off by the time rescuers arrived.
The man suffered injuries to the back of his leg and was flown to Waikato Hospital.
The attack came less than two hours after a woman was flown to Palmerston North Hospital after being attacked by a cow at the dairy farm around 7km south of Dannevirke, off State Highway 2, about 3.45pm.
Palmerston North Rescue Helicopter pilot Marc Bridgman said he believed the attack involved headbutting, not biting or stomping.
"Essentially she was out in the paddock and the cow had just taken a shine to her and had a few goes at her," he said.
"She obviously couldn't really get away from it."
Mr Bridgman said the woman had been moved over the fence away from the cow when the helicopter arrived.
She was discharged from hospital late yesterday.
Federated Farmers dairy vice-chair Robin Barkla said people needed to be more vigilant around calving season.
"The beast's a bit hormonal and a bit confused and the maternity instinct kicks in - it's a very strong instinct. Don't get between mum and the calf basically."
Dogs were also likely to "really get them going".
Mr Barkla said cow attacks were "a very rare occurrence", but Federated Farmers president Bruce Wills said they were common, especially during calving season.
"Cows must be respected especially at this time of year," he said.
"My breeding cows are right in the middle of calving, and it would be a stupid thing to do to get in between a cow and her calf. It's mother nature and maternal instinct.
"They are unpredictable to the point where you can walk through a paddock and have to be aware of how they are standing, what they are doing with their head - it's almost like a sixth sense farmers need to have."
Mr Wills said despite being badly injured after a bull attack earlier in the year, he was still more wary of cows.
"As a farmer with 700 head of cattle I am more respectful of a cow when they are calving than I ever am of a great big bull.
"A good cow is 500 or 600kg, so you've got half a tonne and if that gets a bit agitated and they are protecting their calf, who knows what can happen."
