US animal rights activists have interrupted Australian Foreign Affairs Minister Julie Bishop's appearance at a Los Angeles university.

The activists, holding up bloody, graphic photos of livestock and calling for an end to Australia's live animal exports, held their protest during a question-and-answer session on Friday on the UCLA campus as part of the G'Day USA program.

"Can I talk to you later?" Ms Bishop asked activist Amanda Copeland.

Ms Copeland declined the invitation and kept describing what she said was the inhumane treatment of Australia's live export animals.