Xanthophyll - It's What Makes Egg Yolks Orange

There is nothing more beautiful on a breakfast plate than a vibrant orange egg yolk, shimmering like a miniature sun. But does a bright orange yolk mean that the egg is more nutritious or tastier? Not necessarily.

A bright orange yolk doesn't mean the egg is fresh, it doesn't mean that the hen who laid it was treated or fed well, and it doesn't even mean that the egg came from a free-range hen.

A common misconception is that the more orange the yolk, the more nutritious the egg or that it had to come from a free-ranging hen.

It is true that chickens who free-range normally do lay eggs with deeper, darker yolks because they have a diet that includes grasses, herbs and weeds that contribute to yolk color.

Their eggs may be more nutritious due to their natural, varied diet, a commercially raised chicken can be fed feed that has ingredients such as corn and marigolds in it that will boost the yolk color as well.

Interesting factoid: the more yellow the 'white' of an egg (the albumen) is, the more riboflavin (Vitamin B2) that egg contains.
Similarly, even if you don't free range your chickens, there are ways for you to boost the color of your backyard flocks' egg yolks while increasing the quality of their diet, but not exposing them to the inherent risks of free-ranging.

So let's take a look at what causes the color.  Carotenoids, including carotene, lycopene and xanthophyll, are natural pigments that are found in such foods as:

red cabbage
sea kelp
Swiss chard
turnip green
and the leaves of most green plants. 

These various pigments contribute not only to egg yolk color, but also to the color of hens' feet and beaks, and more noticeably the feet and bills of ducks.

Any excess pigment not used to produce eggs is stored in feet and bills/beaks.

So one sign of a good layer is a pale bill with very little bright orange and the greenish color of the bill showing through (normally covered up with the bright orange color).

The males (roosters and drakes) who don't lay eggs tend to have very orange feet and bill/beaks as long as their diet includes adequate levels of the pigment.

Other carotenoids such as beta-carotene and canthaxanthin don't contribute directly to yolk color, but they do contribute to healthier eggs since both are converted to Vitamin A and help prevent the oxidation of vitamins in the eggs.

The DSM Yolk Color Fan is a widely accepted scale to judge yolk color. Surprisingly enough, yolk color preference varies depending on who you ask.

While people in the UK tend to prefer eggs with yolks in the 8-10 range, while New Zealanders like their yolks to be  in the 11-13 range and Germans like theirs closer to 14!