She'd arrived at the calf-rearing shed about 8am one day in August 2007 to find other workers looking in shock at the dead and injured animals.
"I cried. I cried and cried and cried. And then I was pretty angry because we weren't allowed to finish the rest of them off until the police got there."
Moore has been frustrated the jury, who last month acquitted Macdonald of murdering his brother-in-law Scott Guy on July 8, 2010, was not allowed to know about the atrocity.
They did not know that Macdonald had already pleaded guilty and was awaiting sentencing for slaughtering the calves, as well as committing arson on a duck-shooting "whare" and destroying 16,000 litres of milk from a farmer's vat.
Boe, 22, and Macdonald, 32, had both worked on the Guys' Feilding farm. Boe, who was living in Queenstown at the time of Guy's death, is understood to be serving a prison sentence.
Macdonald has been acquitted of murder, but remains in custody awaiting sentencing next month for the vandalism and killing the calves.
His wife Anna, the sister of murdered Scott, has left Macdonald and last month changed her name on her Facebook page back to Anna Guy.
And she is not the only person distancing herself from Macdonald, whose actions have dismayed former friends and neighbours.
Moore said: "I've just been angry that I haven't been able to say anything but that's all I have wanted to do."
She had never met Macdonald or Boe but said their behaviour was "disgusting" and was a senseless act of revenge after her boss Paul Barber caught them poaching in the middle of the night on the neighbouring farm of Graham Sexton.
"If the calves had been all dead, it wouldn't have been quite so traumatic. I mean, there's no reason to kill 20 beautiful calves."
Police had investigated at the time but not caught the pair until April last year when Boe was interviewed as part of the investigation into Guy's killing.
Chanelle Bullock, sister of Scott Guy's widow Kylee Guy, said the revelations of the slaughter, arson and sabotage "clearly show the nature of Ewen Macdonald. He is a ticking timebomb".