SECRET footage at a Laverton knackery showing horses being belted and dragged while still alive has prompted Werribee Open Range Zoo to review its meat supply arrangements.
Footage filmed by the Coalition for Protection of Racehorses during Melbourne Cup week has prompted outrage from animal welfare groups.
It shows horses being repeatedly hit on the head. Another horse is shown being shot and then dragged along concrete while apparently still alive, before being shot again and having its neck slit.
Zoos Victoria spokeswoman Judith Henke said the Laverton knackery had supplied meat for carnivorous animals at Werribee and Melbourne zoos.
She said the zoos immediately cancelled their supply following the revelations and would source meat elsewhere.
"Werribee Zoo has lions, tigers and other big cats, and horse meat was very lean and a good addition to their diet," Ms Henke said.
"We obviously had no idea that their practices were inhumane.
"Zoos Victoria has also instigated a review of all other meat supply arrangements . . . to ensure that all suppliers adhere to the organisation's animal welfare commitments and comply with the appropriate state and federal requirements."
In the video, loud whacking noises can be heard each time a horse is hit on the head with metre-long sticks.
A worker, who did not want to be named, told the Weekly it was just a "little tap".
"Those things are pretty soft that they use. Everyone says, 'Oh, they're sticks.'
"It's more like a little tap. It's nothing hard."
He said the horses were either "unwanted or dangerous" and were being killed "the best way we can".
He said the video footage was being reviewed by vets. "They do everything by the rules. All they do here is they kill unwanted horses. They are either dangerous or unwanted.
"They go to the auctions and buy them at the auctions. No one wants them so they get them at the auctions.
"The most humane way of killing a horse is a bullet through the head because they're dead before they hit the ground.
"Everyone says they should use the medication, but that is full of painkiller and that stops their heart, so in other words they're having a heart attack."
Ward Young, of the Coalition for Protection of Racehorses, said the footage showed horses being hit in the head more than 60 times and spoke for itself.
"Most reasonable people who see that footage will be shocked and rightly so because the horses don't die as they hit the ground or beforehand.
"As our video footage shows, there was one horse that was shot in the head and dragged more than 60 metres across concrete and gravel where it was found to be still alive.
"The worker's then shot it again and then cut its throat and the horse was still alive after that writhing around, lifting its head off the ground, for up to four minutes before it finally took its last breath."
The RSPCA is investigating.