The stunt was designed to bring to public attention to what the organisation sees as a major cause of the destruction of Amazon rainforests.
It was timed ahead of today's speech by environment secretary Caroline Spelman at farming and food conference 'Feeding Britain Two', run by the Smith Institute.
Friends of the Earth would like a new law put forward to support British farmers who use home-grown feed.
Friends of the Earth's senior food campaigner Vicki Hird, said: "When it comes to food and farming, ministers are ignoring the meatiest issue of all – the massive environmental hoofprint of our factory farms.
"The government is propping up a system that links the meat and dairy on our plates to wildlife and rainforest destruction in South America.
"We don't need planet-wrecking factory farms to feed a growing population – and we don't all need to go veggie either.
"Ministers must back our new law to help farmers to feed animals a home-grown diet, and people to eat less and better meat."
Friends of the Earth members were also driving recruitment for the movement for rainforest-free food at www.jointhemoovement.com.