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"Tastier" blue eggs could be in supermarkets soon

British diners are more used to the normal, light-brown variety - but blue chicken eggs could make a surprise appearance on supermarket shelves.

Blue egg (Wikimedia Commons)

British diners are more used to the normal, light-brown variety - but blue chicken eggs could make a surprise appearance on supermarket shelves.

Nottingham scientists have solved the riddle of why some chickens lay bright blue eggs - which some claim are healthier than “normal” eggs.

Others say the eggs taste better and break more cleanly, according to the University of Nottingham team, whose findings could pave the way for blue eggs becoming a mass-market treat.

Chickens which lay the eggs are sometimes referred to as “Easter eggers.”

Blue eggs first appeared in South America  between 200 and 500 years ago - in the native South American chicken, the Mapuche fowl.


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The strange colour is actually the result of a harmless retrovirus which infected the chicken - and their European descendants, Araucana.

The results could allow further research into creating blue eggs “to order” if demand is there.

The blue pigment is due to a unique quality of retroviruses - it’s possible for genetic material from a retrovirus to become permanently incorporated into the DNA of an infected cell.

The retrovirus caused chickens to accumulate  a green-blue bile pigment called biliverdin in the eggshell - but the survival of the “blue eggs” through the centuries must have been due to chicken breeders, the researchers say.

David Wragg a BBSRC doctoral research fellow, said: “The unusual egg coloration must have attracted the attention of the owners, who must be praised for having selected the trait in subsequent breeding.”

Professor Olivier Hanotte said: “This is an important discovery because some of these rarer native breeds of chicken with this unusual egg colour and high quality have become low in number and are in danger of disappearing if not conserved and indeed promoted by agriculture.”

The finding could also have implications for our understanding of other birds and their eggs, the researchers say.

Dr Joram Mwacharo said: “Of course it’s not only some breeds of chicken that produce blue eggs. They are commonly found across species of birds including those that lay blue eggs as well as non-blue eggs within a single population, like the cuckoo and guillemot. It's therefore entirely possible that retroviruses could be playing a part in the diversity of egg colour and patterning across avian species more generally, but this remains to be studied.”