Weird Eggs 101: The Oddities Explained (or What’s a Fart Egg?)

If you buy eggs from a store they are graded and those with imperfections aren’t sold. Once in a while you might see flaws in a farm egg but you probably haven’t given it a great deal of thought. Here’s the lowdown on some egg oddities.

Double yolks commonly occur in new layers when yolk release is mistimed and two yolks travel down the oviduct together. Older hens tend to lay larger eggs because the oviduct loses elasticity over time. A double-yolker rarely hatches.

Eggs with no shell feel rubbery because the membranes are on the outside. These irregular eggs are commonly produced by new layers but can result at any time from stress or often from calcium, phosphorous or vitamin D deficiency.

High environmental temperatures are the most common cause of thin-shelled eggs. A hen’s increased rate of respiration interferes with calcium carbonate production and shell formation. Older hens generally produce thinner shells as their oviducts wears out.

Egg shells can have different textures caused by a number of factors, from excess calcium or vitamin D intake (pimples that can be scraped off) to double-ovulation, disease, a defective shell gland or rapid changes in lighting (sandpaper shells).

When an egg is delayed in the shell gland, a second egg coming down the oviduct will bonk into it and rest alongside the first egg, causing a flat, wrinkled side.

Oddly coloured eggs are the result of being unevenly pigmented while in the shell gland pouch.

An egg within an egg occurs when, for some unknown reason, an egg almost ready to be laid reverses engines and backs up into the reproductive tract, where it meets the next egg in progress. The first egg receives more albumen, membranes and shell before being laid.

Tiny eggs containing no yolk are referred to as fairy, wind, or fart eggs. (I don’t make this stuff up!) These irregular eggs are also common in new layers when the reproductive system is not yet synchronized but can also occur in older hens when a piece of tissue from the oviduct breaks free, tricking the hen’s reproductive system into treating the tissue like a yolk and creating an egg.

Occasionally I get some of these types of eggs but you’re unlikely to see them. Usually only double-yolkers make the cut for quality control for you, my paying customer. We, the farmers, eat the oddities – the shells may be imperfect but those little orbs are perfect on the inside.

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About author
I live on a small Gulf Island in the Pacific Northwest off the the coast of British Columbia.

I've kept chickens for the last 9 years and although I have some purebreds I love to breed crosses that look interesting (i.e. crests, muffs, beards, frizzles, patterned, spangled, etc) and also lay coloured eggs.

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This is great - many of the most common egg issues summed up in a single, clearly written article ... Eggcellent!
This article is very accurate, and yes, fart egg is a weird name:lau


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