The Government has commissioned research into gassing TB-infected badgers in their sets – more than a year after a West Country farmer said it was the only practical way of culling the animals.
The six-week cull to test the effectiveness of trap-shooting and free shooting of badgers in the fight against bovine TB ends in West Somerset this week.
Unconfirmed reports early in the process suggested that only three or four badgers a night were being killed, compared with the 50 per night needed to meet the area's official target of more than 2,000.
The Department for Food, Environment and Rural Affairs stipulated as part of its licence that 70 per cent of the badgers in the cull zone must be killed. A similar cull began a week later in Gloucestershire and ends in a week's time.
The aim was to kill a total of 5,000 badgers.
Anti-cull campaigners have been attempting to disrupt the work and the RSPCA is amongst those organisations which have condemned the method.
They said animals could be injured, not killed by the marksmen and then crawl away to die. They also said that it was wrong to target infected and uninfected animals.
Dairy farmer and entrepreneur Derek Mead, from Weston-super-Mare, warned last year that the pilot cull was "deeply flawed". He said then: "It won't target diseased badgers and will show farmers in a very bad light indeed."
He co-founded the Badger Welfare Association, dedicated to maintaining a healthy, balanced badger population, and campaigned for funding to build on the work of Okehampton farmer Bryan Hill, who has expertise in identifying infected setts.
He said an unofficial experiment in Devon in 2005 had shown that gassing diseased setts reduced bovine TB cases by 90 per cent, far greater than the 16 per cent reduction found in a ten-year culling trial that ended in 2007.
The gassing of badgers using cyanide was banned 30 years ago because it was considered inhumane, but many farmers believe carbon monoxide poisoning would be a painless way of killing animals in those setts that have been infected with tuberculosis.
Peter Kendall, president of the National Farmers' Union has welcomed the decision by the Environment Secretary Owen Paterson, to commission research into gassing and other "alternative sett-based culling methods".
He said the "holy grail" for cattle farmers, who lost 28,000 animals because of bovine TB in England last year, was a culling method that allowed them to focus on diseased setts.
He said that gassing would be easier than shooting because it would happen during the day when badgers were in their setts.
However, he admitted that the public would still need to be persuaded that gassing was humane.
Queen guitarist and the high-profile leader of the fight against the trial cull, Brian May, tweeted: "Incredible that the NFU was saying they didn't want to EXTERMINATE badgers. And now they want to gas the setts ??! Unbelievable."
Defra has said that: "It is not possible to say at this stage if or when gassing is likely to be a realistic or humane method of culling."
One concern about the method is that the gas might not fully reach every part of a sett, and some animals might survive but be left brain-damaged by the gas.
Defra said the research was "predominantly desk-based" and no animals or gas were being used.