Wednesday, 19 November 2008

Double Yolk

Well, that hasn't happened to me for years (literally). About 1 in 1000 eggs has a double yolk so it isn't all that rare. In some countries, markets sell cartons of double yolked eggs. If you reckon on using about nine eggs a week, as we do, then you would expect to get one every two years. But it is certainly many years since I had one despite always using free range eggs and not battery ones.

Double yolkers happen when ovulation occurs too rapidly or when one yolk somehow gets "lost" and is joined by the next yolk. Double yolkers may be laid by a pullet whose reproductive cycle is not yet well synchronized or, occasionally, by a heavy-breed hen, often as an inherited trait.

You can also have no yolkers (cutely known as 'fart' eggs!), double shelled eggs, eggs without shells, eggs of weird shapes and even a five yolker - which made the Guinness Book of Records.

Photo courtesy of © Michelle Byerly

An egg within an egg happens when an egg that is nearly ready to be laid goes backwards and gets a new layer of albumen covered by a second shell. This extremely rare example of an egg within and egg comes from Michelle Byerly, of Jasper, Texas. The egg was laid either by a Buff Orpington or a Black Australorp in early 2004. The internal egg had no yolk.

According to where you live, a double yolk can mean anything from an forthcoming wedding to a financial windfall to a death in the family. I think I like the middle prospect best!

So would a double yolked egg produce twins, I wondered? The answer, it seems, is probably not, the presence of the two yolks would generally lead to an unsuccessful hatch because the nutritional value of the white is insufficient for two embyros.


  1. This comment has been removed by the author.

  2. I have since learned that Richard had a double yolker about the same time as I got this one. Presumably they were in the same batch.


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