The owner of the slaughterhouse whose worker was caught throwing and bashing calves with a piece of wood before killing them said she knew nothing about it until she saw the video footage.
Animal protection lobby groups SAFE and Farmwatch captured footage from 12 Waikato dairy farms and a slaughterhouse of unwanted bobby calves left in roadside crates, being thrown onto trucks and abused at a Waikato slaughterhouse.
Down Cow slaughterhouse in Te Kauwhata kills bobby calves for petfood manufacture and was one of the companies filmed.
Owner Sheryl Cleaver said she first became aware of the worker abusing animals when she saw the video on television on Sunday night.
Ms Cleaver said the seasonal worker was employed between July and October at the height of the processing season and was no longer with the company.
"If we'd known earlier about what was going on he would have been dismissed immediately."
Ms Cleaver says the company will review its systems and was considering installing cameras in its works, but she was s confident its five full time employees did not treat the animals badly.
"We've seen what the other guys have done and the main person who's dealing with the calves is the slaughterman and the truck drivers - and one truck driver I've seen him so many times and he thinks that [the calves] are almost his babies.
"The trucks pictured picking up calves from the roadside pens with operators throwing calves into the rear doors were not our trucks or operators."
One of the workers filmed tossing calves into the back of a truck was employed by the transport company, Waitoa Haulage.
The company says the man was sacked part way through the bobby season because of how he treated animals.
The Ministry for Primary Industries began investigating in September, when it was given the footage, but is not revealing what stage its inquiry is at.
Its minister, Nathan Guy, said he had little information about the inquiry but was aware Down Cow had been visited in October.
"I don't know the outcome of that visit. That's something that will be considered in the overall investigation.
"Hopefully they can bring these individuals through the New Zealand court system."
Dairy farmers have turned to social media to vent their disgust at the abuse and defend their industry's practices.
One Waikato dairy farmer, Matthew, who did not want his last name to be used, said since the footage had been released, dairy farmers had been getting an unfair rap.
"You're being tarred with the same brush, as with the transport companies and with the people in the slaughterhouses. They're thinking you've abused your animals in the same way when it's not true at all."
Matthew said sending four- to five-day-old calves to the works was one of the worst parts of the jobs, but if people want to continue drinking milk and eat cheese, it was a necessary part of the industry.