A naked man spotted having sex with a horse in broad daylight hid down behind the mare to avoid being identified, a court has heard.

The 67-year-old, whose name was suppressed on Tuesday by Judge Lance Pilgrim at a County Court sitting in Ballarat, used tethers and a milk crate to defile another animal in a separate incident.

The man, who was previously convicted of bestiality in May 2013, pleaded guilty to two charges of bestiality after being filmed by members of the public performing lewd acts on his rural property near Ballarat.

One witness, after spotting the man standing in an "unusually high" position behind a horse tethered to a shed on March 12, went to get a camera to film the incident.

Crown prosecutor Tania Bolton told the court on returning, the witness observed the man, standing on a milk crate, penetrating the horse with his forearm while masturbating.