A man has died after being knocked to the ground by a cow in Geelong, south-west of Melbourne.

The 72-year-old man was trying to catch the cow, which had escaped from the Geelong Saleyards on November 19.

He was taken to hospital, but died of his injuries last Wednesday.

Police are appealing for witnesses to come forward and would like to speak to a female nurse who helped the man at the scene after he lost consciousness, and a young girl, who was also trying to catch the cow at the time.

The loose cow ran for about two kilometres after escaping from the saleyards on Weddell Road, causing traffic chaos.

Two other people were injured when a bus was forced to brake suddenly, police spokeswoman Belinda Batty said.

Anyone with information is asked to contact Crime Stoppers on 1800 333 000.