The stickers, which carry messages like 'dairy is scary', have been branded illegal by one meat boss.
Rod Slater, Beef and Lamb New Zealand Chief Executive, told rnz.com that people 'shouldn't forget that these actions are vandalism'.
"Very simply what they are doing is illegal and they're interfering in the lives of people going about their lawful everyday work and life, he added.
"It just disturbs me that people like this think that they can come in and disrupt a lawful business in the manner that they do."
He told Newstalk ZB he 'doubted people would become vegans after reading the stickers'.
An official statement from Countdown said the store would not condone tampering with food adding that it offers a range of vegan and vegetarian options throughout its supermarkets.
In addition, it said Countdown works 'closely with hundreds of local farmers to provide quality meat' - and that 'good animal welfare is at the heart of these partnerships'.
'Planting a seed'
One UK-based activist told Plant Based News they disagree that people won't become vegan after seeing these kinds of stickers.
"It's not that people are likely to see the sticker and go vegan on the spot," they added, "but it can plant a seed. I like to think that this kind of imagery can make people start to think about the impact their choices make on others.
"For me, it's about making people realize that when they eat meat, they are eating someone, not something. And I think that when people make that connection, they can think about changing their lifestyles."