CALGARY -- Anger was on full display under the hot spring sun as thousands of oil and gas industry supporters gathered on the Calgary Stampede grounds to hear speakers take turns blasting the federal Liberal government for policies they blame for the sector's low level of activity and investment.

Organizers estimate 4,000 people, many wearing black T-shirts reading "The world needs more Canadian energy," came for the event which featured a bluegrass band, free hot dogs and admission to the annual Global Petroleum Show trade show.

The crowd cheered and chanted "Build that pipe" as Saskatchewan Premier Scott Moe called for a national conversation around federal bills C-69 and C-48, reviled by those in the energy industry, because they affect the entire economy of Canada.

They booed when newly appointed Alberta Energy Minister Sonya Savage listed energy sector grievances -- including the failures of the Northern Gateway and Energy East pipelines, delays to the Keystone XL and Trans Mountain pipelines, and the previously mentioned federal bills to revamp the way big energy projects are approved and to declare an oil tanker ban on the north coast of B.C.

Earlier in the morning, Premier Jason Kenney delivered a similar speech in a conference room at the opening of the annual trade show before leaving on a trip through Quebec and Atlantic Canada to sell Alberta's virtues to investors and other premiers.

Kenney's speech was briefly postponed when a man rushed up on stage and grabbed the podium -- saying the premier doesn't represent him before the microphones were muted and he was subdued by police and security officials and dragged away.

"Well folks, there are very few energy producers around the world where you'd see something like that happen," Kenney said after order was restored.

"This is a free, liberal democracy with freedom of speech and we embrace that."

Dmg Events, which mounts the annual petroleum show, says it expects to see about 50,000 attendees this week, down from nearly 75,000 at its peak in spring of 2014 just before world oil prices crashed.