Footage of a cow being dragged face-first along the ground by a tractor was given to the Ministry for Primary Industries (MPI) a year ago, but there has still been no decision on possible charges.
Warning: Some people might find the video in this story disturbing.
Activist group Farmwatch handed hours of hidden-camera footage to MPI last November, after the group went public with its investigation into the treatment of bobby calves.
Some of that footage was broadcast on television, including a slaughterhouse worker shown kicking and throwing calves. That worker was prosecuted by MPI, and sentenced to home detention.
But the group also handed over footage that never went to air, including a 15-minute video in which a cow was hoisted in a hip harness, kicked and dragged along the ground by a worker in a tractor.
The harnesses were not uncommon, or in themselves necessarily concerning, because cows sometimes lost their nerve function when they gave birth and could not stand by themselves.
But Farmwatch spokesman John Darroch said the treatment breached animal welfare laws.
"The farmer had ... come along, and he'd dragged the cow across the field, and her face and front legs are digging into the mud as she's being suspended by her hips."
Mr Darroch said the worker in the footage should be prosecuted under the Animal Welfare Act.
But he said because that piece of video never went to air, it had been put on the backburner by MPI.
"Eleven months to carry out a basic investigation, and to decide whether or not there's enough material to lay charges, I just don't think is good enough."
Veterinary Association head of veterinary services Callum Irvine, who was shown the video by Checkpoint, said the clamps might look draconian to some New Zealanders but were common within the dairy industry.
However, he said the way they were used in the footage was a clear breach of animal welfare.
"What we're concerned about in there is that it appears she's suspended in those clamps for a prolonged period of time, certainly more than 15 minutes, which is well beyond what we would recommend.
"In fact, it's a breach of the Code of Welfare."
Mr Irvine cited a specific part of the act that outlawed the dragging of cows while they were in the clamps.
MPI spokesperson Gary Orr confirmed it was investigating the case, but said it had not made a decision as to what to do with the footage.
"MPI began a thorough and methodical investigation after receiving this footage - parts of which are obviously distressing and disturbing," he said.
"The investigation is all but complete and a decision is imminent. We will be releasing our findings publicly as and when the inquiry concludes.
"As part of our investigation, we spoke to the farmer at the centre of the footage. The file has received rigorous legal scrutiny and is currently under final review."
