Researchers at the Roslin Institute at the University of Edinburgh found the way vitamin A is converted by the skin on the Transylvanian naked neck chicken combined with a protein in the flesh allowed it to shed feathers around its neck.

A total of 12 scientists worked on the research from Heriot-Watt University in Edinburgh and locations in France, Mexico and Switzerland.

Denis Headon, who led the research at the Roslin Institute, said: “We found that the substance produced from vitamin A on the skin combined with the protein BMP12 contributes to its vulture-like appearance. A genetic mutation affects BMP12 contributing to the loss of feathers. The skin on the neck is therefore primed to lose feathers as a result of this. Not only does this help our understanding of developmental biology and give insight into how different breeds have evolved, but it could have practical implications for helping poultry production in hot countries, including those in the developing world.”

Researchers analysed DNA samples from naked neck chickens in Mexico, France and Hungary to find the genetic mutation. Skin samples from fertile chicken eggs were also analysed using mathematical modelling.

Transylvanian naked necks, which are thought to have originated from the north of Romania, have been around for hundreds of years and were introduced to Britain in the 1920s.