At least three of the bobby calves were killed on impact, while another 10 were still missing.

Camperdown police attended the scene, about one kilometre west of Pirron Yallock, at 6.40pm Tuesday.

Officers recovered six animals, three of which were alive. RSPCA Victoria president Dr Hugh Wirth slammed the driver and said it was the worse bobby calf case he had heard about.

"It's not just distressing, it's bloody awful," he told The Standard late yesterday.

"It's pure negligence and thoroughly sickening. Accidents do happen but to keep on driving and not check your load is disgraceful.

"I hope this incident is being investigated."

The truck collected the load from the Camperdown saleyards and was travelling east on the highway.

Camperdown police found calves at least two kilometres apart. Senior Constable George Hasiotis said he initially thought only one calf was involved.

"We arrived and a calf had collided with a car, which sustained minor damage. The calf was dead," he said.

"The driver then told us there was another calf, which we found deceased. Then we found another running along the road.

"We were able to put that one in the back of the divi van."

Senior Constable Hasiotis spotted several more calves and realised they were likely to have come from the one transporter as they had different ear tags.

He notified the truck driver, who was not charged. But police and Colac Otway Shire local laws officers are investigating.

General manager of bobby calf marketer Vic Stock Will Crozier said the incident was "distressing".

The transport did not belong to Mr Crozier's fleet. "Incidents like this are regrettable but are what happens when you have unrestricted access to and from the saleyards," Mr Crozier said.

"When the regulatory authorities look at this to see how it was allowed to happen the scrutiny on saleyards will become tougher, which is a pity.

"Every door which closes on a farmer is one less option to seek a competitive price."