Proudfoot said in previous years the breakfast had invited media on the understanding discussion would not be reported.
KPMG's barring of media this year, Fieldays 50th, was "partly" in response to guest feedback from last year's event, he said. Some said they felt constrained from asking questions or making points because the media was present and some had reported on the event, Proudfoot said.
"We have made the decision to have no media attending this year and that is the position we have taken."
About 120 business leaders attended last year's breakfast at Mystery Creek, near Hamilton.
KPMG's annual agribusiness breakfast at the Canterbury A&P Show had always barred the media, he said.
Damien O'Connor's office said it would make his speech public. Shane Jones' office said he didn't have a written speech.