The bungled experiment happened during a study by AgResearch scientists at Ruakura, Hamilton, to find human fertility treatments through GM cows' milk.
AgResearch is studying tissue from one of three dead calves to try to find out what made the ovaries grow up to the size of tennis balls rather than the usual thumbnail-size.
Details of the deaths - in veterinary reports released to the Weekend Herald under the Official Information Act - have reignited debate over the ethics of GM trials on animals.
AgResearch's applied technologies group manager, Dr Jimmy Suttie, said he did not see the deaths as a "big deal", and they were part of the learning process for scientists.
But GE-Free NZ spokesman Jon Carapiet said details of the calf trial showed the animal welfare committee overseeing AgResearch's work was "miles away from the ethics and values of the community".
The calves died last year, aged six months. They were formed when human genetic code injected into a...