Suggestions that local authorities could save money by using sheep and cattle to cut grass "trivialised" the damage being done to services by the Government's austerity drive, unions representing over a million council workers have said.
The TaxPayers' Alliance published 201 ways it believed local authorities could save money and reduce bureaucracy, ranging from freezing recruitment, ending automatic pay rises for staff and rewarding council tenants for carrying out their own repairs.
Another suggestion was using cattle and sheep to graze on council land rather than spending money on grass cutting.
Unison's head of local government, Heather Wakefield, said: " Many of these ideas are trivialising the damage that is being done to our communities by central government cuts to local authorities, with councils across the country being decimated and some in danger of going under.
"Local councils have faced unprecedented cuts in funding under this Government and they are now bracing for a further cut of 10% next year. Suggestions such as outsourcing grass cutting to a consortium of bovines in order to save on the cost of a few lawnmowers is trivialising the serious damage that is being done to local communities.
Unite national officer Fiona Farmer said the "self-appointed and unelected" alliance was proposing "'wacky" ideas at a time when 500,000 local government workers earned less than the current living wage.
She said: "The credibility of the TaxPayers' Alliance has to be seriously questioned when ideas taken from medieval times, such as grazing sheep, are wheeled out in its endless quest for publicity.
"Has the alliance worked out how much it is going to cost to buy these animals and pay the substantial veterinary bills? The prospect we face is hundreds of these animals freely roaming around municipal parks ignoring health and safety considerations when children are playing - and being a prime target for urban rustlers.
"Councils are already looking at sensible ways to save money while trying to maintain services for often very vulnerable people against the swingeing cuts on council budgets.
"After a three year pay freeze, job losses and cuts to terms and conditions, local government workers are the lowest paid in public services - their pay and conditions are being taken back years, although not quite as far, yet, as the Middle Ages."
Jonathan Isaby, Political Director of the TaxPayers' Alliance, said: "Far too often we hear unimaginative councillors insisting that they have no choice but to raise council tax and increase the burden on already hard-pressed families.
"But there are literally hundreds of ways in which local authorities can save money before even thinking about increasing the council tax."
Local Government Secretary Eric Pickles said: "This report exposes how there is still massive waste in the public sector. There is significant scope for town halls to save taxpayers' money, helping keep council tax down and protect frontline services.
"Councils which complain about so-called cuts need to read through this report and justify their spending to local taxpayers. Central government could learn many a practical tip from this too."
A spokesman for the Local Government Association said: "The TPA seems to have lost its bearings. This is a list of things councils have been doing for years peppered with a number of frankly ridiculous ideas, some of which are downright dangerous.
"Councils are getting on with the serious business of saving money through sensible, well thought-through reforms which will keep council tax low and go some way to protecting local services from the 43% cut in funding from central government."