Back in the 1970s, it was common for most commercially produced eggs to be white. With the rise in healthy eating, and a move to wholemeal bread and more natural foods, white eggs fell out of favour with the perception amongst the public that the larger brown eggs were healthier.
Since the 1980s the UK egg industry has produced almost 100% brown shelled eggs for high street retailers. As a result, there are now very few white egg-laying flocks in the UK; down to an estimated 250,000-300,000 of the 36 million egg-laying birds in the UK. Believe it or not, there is no difference in the taste or the nutritional value of eggs regardless of colour. When people think of white eggs in the UK, their mind instantly goes to what they’ve seen on American TV and film, because in the USA white eggs still tend to be the norm.
So why do hens lay different coloured eggs and what determines it? Next time you look at a hen, have a look at her earlobes (yes really). There is an old wives’ tale that the colour of your hen’s earlobe denotes the colour of the eggshell. Supposedly, hens that have white ear lobes will lay white eggs. However, eggshell colour is actually determined by the breed of the hen and her genetics.
Other factors that have a bearing on eggshell colour
One factor is age. Older birds tend to lay paler eggs. This also has a direct correlation to the size of the egg. As older birds tend to lay bigger eggs, the same amount of pigment is spread over a larger surface area. A brown egg layer that goes through a moult will lay darker eggs after the moult.
Another factor could be disease. Exposure to some diseases does affect the shell colour. In particular, Infectious Bronchitis can change the colour of the eggshell, it can also cause wrinkling on the egg’s surface.
Certain intestinal worms can cause damage to the intestinal wall which results in a reduction in nutrient absorption and this may cause pale shells and pale yolks.
A big factor that can change eggshell colour is stress. The bulk of the pigment is transferred to the cuticle three to four hours before laying. Any stress causing a delay in the egg leaving the oviduct may result in a thin layer of calcium being deposited on the egg giving a greyish or bleached appearance. Equally, a premature egg may not have enough pigment deposited and will also affect the colour.
Like us humans, too much or not enough sunlight can affect a hen. Pale eggs occur in hens exposed to large amounts of sunlight due to Vitamin D 3 production. On the other hand, not enough sunlight may cause your hens to naturally stop laying eggs due to a hormonal response like in winter when the days get short. It’s all about balance!
If you want to know more about the eggs your hen lays, we have many more health and welfare articles on our website! Check them out here.