“Horrifically deformed” turkeys have been discovered at a factory farm named as a supplier to some of the UK’s biggest supermarket chains.

Secretly taken video footage shows crippled birds unable to walk, with missing feathers and exposed skin, and appearing unhealthy or suffering. Sick birds were also recorded being attacked by others.

The turkeys would have lived in the shed for between eight and 26 weeks before being slaughtered.

The centre, at Sudbrooke, Lincolnshire, is run by the Faccenda Group, which is owned by Avara Foods, one of Britain’s largest food manufacturers, which produces more than 100 million turkeys and chickens each year.

The company says it supplies some of the UK’s largest retailers, including Asda, Morrisons and Sainsbury’s, as well as restaurant chains.

Morrisons said it was unable to confirm whether Faccenda supplied it with turkeys this year, having sourced them elsewhere last year. Faccenda has previously said it worked with Sainsbury’s.

Undercover investigators from animal-rights group Surge filmed the clip in January but have released it as shoppers were planning their Christmas dinners to expose what they describe as the “shocking toll of suffering” behind the turkey products in supermarkets, eateries and takeaways.

The poultry company says it has addressed the problems and audits showed no problems, but Surge says their findings highlight how “woefully inadequate” animal welfare regulations are.

When a bird collapses it can be vulnerable to being picked on (Surge)

The witnesses said they saw many of the birds had lost feathers, which they believed was due to stress and health problems or injuries inflicted by other birds because of their confined, unnatural housing.

Others were filmed struggling to stand or walk, or collapsing under their own weight as, like most turkeys in Britain, they had been bred to grow more quickly than their legs can take.

Ed Winters, co-director of Surge and known as “Earthling Ed”, said the birds were “horrifically deformed”.

“Undercover investigators working for Surge have discovered turkeys suffering horrifically in a standard UK turkey farm,” he said.

“These animals, treated as nothing but commodities, were shown to be severely lame and in terrible pain – a consequence of consumer demand for their flesh.”

Experts say most turkeys sold as carcasses or used in products such as burgers, slices and en croutes are bred to put on weight so quickly that their limbs cannot support their bodies.

The birds either become lame or their legs can break, leaving them in intense pain and unable to walk or even stand, which in turn means they cannot reach food or water supplies.

According to Compassion in World Farming, lame birds are susceptible to aggression from others.

These animals were severely lame and in terrible pain because of consumer demand for their flesh Earthling Ed

Wet litter underfoot and ammonia-filled air cause “painful skin and foot sores and eye and respiratory problems”, it says.

With a turnover of more than £500m, Faccenda is one of Britain’s largest privately owned businesses, and also supplies chicken to Nando’s. Avara also says it sells chicken, turkey and duck to the nation’s most popular supermarkets and restaurants.

The facility was typical of most non-organic UK farms providing birds for meat, according to Surge.

“This is the bleak reality of what life is like for farmed animals in the UK, a country that preaches to have the highest welfare standards in the world,” said Mr Winters. “What this shows is that welfare regulations will never be able to safeguard these animals.”

Surge said that all security and biosecurity measures needed were taken by the investigators and that no laws had been broken.

Asda and Sainsbury’s both referred to a statement by the British Retail Consortium but declined to comment further on this issue. The statement said: “Our members take their responsibilities to animal welfare very seriously and work closely with trusted suppliers so that high welfare standards are upheld. They have strict processes in place and will thoroughly investigate any evidence of non-conformity to ensure that any problems are immediately addressed.”

We should have identified and removed these birds sooner but we are concerned about the practice of breaking into farms Avara Foods

Jim Roberts, of Avara Foods, a joint venture owned by Faccenda, said the undercover footage had been edited “to focus on a small number of turkeys that were suffering with health issues, which should have been addressed sooner”. The problems had been addressed with the farm, he said.

“As soon as we saw this film, in March, we immediately took action. We identified the farm involved and requested three independent audits, as well as increasing the number of visits by our own team,” he said.

“None of these audits reported concerns about the health of the birds on site or the environment. However, we are not complacent and remain vigilant. We will continue to monitor and always encourage anyone with concerns to contact us so that we continue to meet the highest standards.” The company also released its own video of its turkeys.

Sudbrooke farm responds to allegations of animal abuse with footage from their turkey shed

“As you can see from our unedited video of 16 April, our turkeys are typically healthy, active and display the natural, inquisitive behaviour you would expect,” he said.

“We accept that the undercover footage shows turkeys that are having difficulty walking and that we should have identified and removed these birds sooner. We remain concerned about the practice of breaking into farms and disturbing birds with bright lights while they are sleeping.”

Aldi said it had not been supplied by the site for at least the past 12 months, and Tesco said it would not be buying turkeys from Sudbrooke this Christmas.