Traffic was disrupted for a period of time after 4pm on Sunday, when police said a horse float containing a cow rolled.

Sally Phillips and her family were travelling on the highway towards Bendigo when they came across the scene.

The trailer was on the same side of the road as they were, Ms Phillips said.

The cow was initially on that side of the road, too, but it crossed into the middle of the highway, and then the opposite side.

"We were sitting there for a while and the kids started filming," Ms Phillips said.

The footage shows the cow on the highway, in the Melbourne-bound lanes, with people trying to shepherd it to safety.

Police were in attendance and were managing the scene.

The footage ends as Ms Phillips and her family are given the go-ahead to resume their journey.

The cow was up on the embankment by that stage, with people trying to ensure it remained away from harm.

Ms Phillips said both sides of the highway were shut for a period of time.

She said road users behaved responsibly, slowing down even before police arrived.

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Police had yet to arrive when her family came across the scene.

The sight of a bit of commotion prompted her family to slow down and switch on the hazard lights - a cue other road users were responsive to, Ms Phillips said.

She initially thought there might have been a crash, as there was debris on the road and damage to the float.

"Something's happened and [the cow] has escaped," Ms Phillips said.

It is not known what happened to the cow.

Ms Phillips and her family made it home safely, just a bit later than they had expected.

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