One opponent of the city council's plan to produce its own meat supply claims it would be "like opening a new runway at an airport" – because of the greenhouse gas emissions caused when cows break wind and burp.

Bristol City Council announced in February that it wanted to acquire Stoke Park, the 200-acre parkland in front of the landmark Dower House alongside the M32.

This would allow it to graze cows on the land, and start producing beef for schools and restaurants.

But critics say the amount of methane a herd would create would be harmful to the environment.

Methane is a 21-times more powerful greenhouse gas than carbon dioxide, the gas produced by the exhausts of cars and other vehicles using the M32 and most commonly measured in assessing how human activity affects global warming. Researchers claim cows produce up to 10kg of methane each per year.

The council's ruling Liberal Democrat cabinet is being urged to approve the plan when it meets on Thursday.

The Bristol-based Soil Association has been involved in planning how the site would be managed. Phil Stocker, director of farmer and grower relations, said it would be a small-scale operation of 30 breeding cows providing calves for beef production after two-and-a-half years.

There would be between 70 and 90 livestock on site at any one time, with the aim of producing six tonnes of beef after two years.

Mr Stocker said: "We're looking at a traditional breed, something like a long horn.

"They're an attractive breed that graze well and produce a distinctive and tasty beef. The beef produced would be sold or made available for the Bristol area – there is quite a lot of community interest."

Vegans eat no animal products, including milk and eggs.

Organiser of the Bristol Vegan Fayre Tim Barford, 45, of Blackboy Hill, condemned the proposals as environmentally unfriendly and unhealthy.

He said: "Livestock is responsible for 18 per cent of global emissions, that is more than transport, which is 13 per cent. Effectively what they're proposing is like opening a new runway at an airport. In a time when we're trying to cut back on global emissions it's absolutely mad.

"I suggest they should use that land to grow crops to feed people, or grain as a gift to the developing world that is suffering from starvation."

Bristol Parks Forum and community group Lockleaze Voice have both supported the acquisition of the park, provided adequate public access is ensured and wildlife protected.

Bristol East MP Kerry McCarthy, who is a vegan, raised the issue of methane producing cows in Parliament last week.

But she said the Bristol venture would be too small to have a significant effect.

She said: "I don't think you can regard a field full of cows as a threat, it's more about the collective impact.