Media playback is unsupported on your device Media caption NFU president Peter Kendall: "I've seen farming families moved to tears round kitchen tables"

A badger cull is under way in England despite protests, the National Farmers' Union has confirmed.

About 5,000 badgers are expected to be killed in controlled shootings over six weeks in Somerset and Gloucestershire.

Supporters say the cull is necessary to tackle bovine TB, which can be spread from infected badgers, but opponents say it is inhumane and ineffective.

The RSPCA said it was "saddened", while anti-cull protesters held a vigil as the pilot began, initially in Somerset.

It is understood the cull in Gloucestershire will start later this week.

In a letter to members, National Farmers' Union (NFU) president Peter Kendall said: "This is an important step not just for cattle farmers but for the whole farming industry.

"I know that many of you reading this will have suffered the misery of dealing with TB on farm - some of you for decades - and I hope now you will feel that something is finally being done to stem the cycle of infection between cattle and badgers."

He added that he hoped the culls would show a reduction in TB in cattle, and that more people would understand why they were "absolutely necessary".

Image caption Many people are opposed to the cull and activists have vowed to continue their protest

But one activist from Forthampton, near Tewkesbury, who would only give her name as Lynne, said the cull was "utterly unacceptable" and described it as the "extermination of the badger on British soil".

She said activists would be calling on people from across England to join their demonstration, by "interfering with the cull" and protest walks.

England's badger cull Badgers are being shot by marksmen in the west of England as part of measures to protect cattle from bovine tuberculosis (TB)

The marksmen will shoot the badgers at night after putting food such as peanuts outside their setts. This method has not been formally tested before

Badgers are thought to pass on the disease to cattle through their urine, faeces or through droplet infection, in farmyards or in pastures

However, the extent of their role in the spread of bovine TB is not clear since the cows can also pass on the disease

According to one newspaper report, cage-trapping badgers for vaccination (or shooting) costs about £2,500 per hectare, whereas shooting them as they run freely costs about £200 Q&A: The badger cull explained Find out more about badgers with BBC Nature

Lynne said she did not believe the cull represented the democratic point of view, was "completely unscientific" and would push infected badgers into cull-free zones.

Environment Secretary Owen Paterson said the infection needed to be dealt with in both badgers and cattle.

"We have to use every tool in the box because TB is so difficult to eradicate and it is spreading rapidly," he said.

"If we had a workable vaccine we would use it... a vaccine is at least 10 years off."

Mr Paterson denied suggestions from anti-cull campaigners that the government was simply trying to appease the farming community.

"In the Republic of Ireland the disease was rocketing until they began to cull."

He said there had been a "significant reduction" in the disease in Ireland, where culling began in the 1980s.

Cull 'scandal'

Scotland is classified as being free of TB. In Wales, vaccination trials are under way. Northern Ireland is researching a mix of vaccination and culling.

Media playback is unsupported on your device Media caption Owen Paterson MP: "It is pointless vaccinating existing diseased animals"

"I want to end up with healthy cattle living alongside healthy wildlife," Mr Paterson added.

But Labour's Shadow Environment Secretary, Mary Creagh, said the cull was "not the answer".

"The government's own figures show it will cost more than it saves and it will spread bovine TB in the short term as the badgers are disturbed and spread infection to neighbouring herds.

"We agree with the scientists that it has no meaningful contribution to play in tackling bovine TB."

Lord Krebs, who led the Randomised Badger Culling Trial in the 1990s, said the two pilots "will not yield any useful information".

Farming minister David Heath admitted in correspondence with Lord Krebs that the cull would "not be able to statistically determine either the effectiveness (in terms of badgers removed) or humaneness of controlled shooting".

This was due to the small scale of the pilot culling programme.

Dominic Dyer, of Care for the Wild, which opposes the cull, described the start of the scheme as an "absolute scandal".

"There's no scientific or economic justification for the cull and it may make the spread (of TB) worse not better," he said.

"This is killing without protection - they're not even testing [the culled animals] for TB and they're only monitoring the cull of a small number."

The RSPCA said it was "deeply saddened" to learn that the cull had begun.

Science has shown that this cull is not the answer to bovine TB in cattle Gavin Grant , RSPCA chief executive

Chief executive Gavin Grant referred to the cull as a "misguided attempt to control bovine TB in cattle".

He said the organisation was seriously concerned the methods being used to kill the badgers were "not humane", and the extent of potential suffering was not known.

"It is very likely that many of them are lying injured, suffering a painful death," he added.

Mr Grant backed other opponents who say scientific evidence shows a cull is unnecessary.

"Science has shown that this cull is not the answer to bovine TB in cattle. In fact, it could make things a lot worse."

"Vaccination and better bio-security are the only sustainable and true ways forward."

High-velocity rifles

David Barton runs a closed herd on his farm in Cirencester, Gloucestershire.

"I've lost a third of my herd in the last two years - it's completely devastating," he said.

"These are animals I know, they have characters, and I hear people being very passionate about badgers and I can empathise with them but they're not animals they deal with on a day-to-day basis and they have no idea what farmers like myself are going through.

"I understand people don't like the idea of it (the cull) - I don't like the idea of it but it has to be addressed.

"In this area over 50% of the badgers are carrying TB."

Avon and Somerset Chief Constable Nick Gargan said his force had been preparing for the start of the cull for some time.

"It's their [the government's] call not ours, but we understand we have a supporting role in ensuring that this democratically-elected government can push its programme forward... and similarly to ensure that people who want to protest within the law are able to do so."

Earlier, officers were sent out in Gloucestershire to provide "reassurance".

The cull will involve marksmen with high-velocity rifles using a mixture of controlled shooting and free shooting, with some badgers being trapped in cages first.