Plans to cull badgers to deal with TB in cattle will reduce herd breakdowns by 2.5 per cent but cost farmers "hundreds of thousands of pounds", the Commons has heard.
Shadow environment secretary Mary Creagh said official figures revealed that just 5 herd breakdowns a year would be prevented in each cull area.
The government wants to fight cattle TB in England by allowing farmers and landowners to cull badgers at their own expense, but animal groups see vaccination as preferable.
Speaking during departmental questions, Creagh said: "In a parliamentary written answer to me on September 5 you said the science showed your badger cull would lead to five fewer herd breakdowns per year in each cull area.
"Last year there were over 2,025 confirmed herd breakdowns in England.
"So even with 10 cull areas after 2013, the cull would prevent just 50 herd breakdowns a year, a reduction of just 2.5 per cent in actual herd breakdowns.
"Yet the cost to farmers in cull areas will run to tens, if not hundreds, of thousands of pounds. Why should they bother?"
In response, agriculture minister Jim Paice said the measure would be "expensive" for the farmers involved, but said the industry was anxious for something to be done to tackle the disease.
He told MPs: "Of course it is going to be expensive for the groups of farmers that will be involved, but that is up to them.
"The fact is this is one part of a large package of measures, the rest of which the government is doing."
Creagh retorted: "You say do something, but surely doing something effective is more useful than just doing something."
She referred to comments by home secretary Theresa May who suggested the raised cull could take up police time and divert "scarce resources" from next year's Olympics.
Paice emphasised that no final decision had been made and said the department was in talks with the Association of Chief Police Officers about the cull.
The minister was responding to a question from Graeme Morrice (Lab, Livingston) on what representations have been received from the scientific community on the plans to pilot the free shooting of badgers.
Morrice said the government had "blindly" cancelled 5 out of 6 vaccination trials entered by the last government.
In other exchanges, George Eustice (Con, Camborne and Redruth) asked about the young entrants support scheme in Wales, and said he hoped it could be replicated in the UK to help younger people enter the farming sector.
Environment secretary Caroline Spelman highlighted that the growth review would have a rural strand.
Sajid Javid (Con, Bromsgrove) raised about concerns that young British workers were not taking up jobs on farms.
In response, Spelman said that whilst manual work on a farm is hard work it can be paid quite well "up to £10 an hour on average, so that would seem not to be an impediment".
She told MPs: "Working together with the Department of Work and Pensions we are very keen to make sure that work does pay for our young people."
Andrew George (Lib Dem, St Ives) said many of the European proposals "undermine the competitiveness of British agriculture".
Spelman said the European Commission has just published its proposals for reform of the CAP which she found "disappointing".
"We will do all we can to improve them. We need to have an agriculture which is both competitive and market orientated, that is successful, to attract new entrants," she told MPs.
"What the commission are proposing, at first sight - we need to do more analysis, is extremely bureaucratic and doesn't move us in the right direction."
