The color you see in an egg yolk comes from the diet of the hen; she does not synthesize any yolk color herself. The color in poultry diets is mostly from yellow corn. Other common ingredients with color in your feed may be alfalfa meal, corn gluten meal, and distillers grains. Birds fed diets with barley, wheat, and sorghum lay eggs with pale yolks since they do not have much of the yellow pigment called xanthophyll. All yolk color in feed must come from natural sources which may include specialty feed ingredients such as marigold meal or oil, yellow yeast, etc. Adding color to darken egg yolks can be costly.
If your small flock has access to lush, rapidly growing green vegetation, this will also add a deeper color to your yolks. Notice that it must be lush and green because the birds won’t normally consume mature and stemmy vegetation. If your birds are running free in a large outdoor pen without any green vegetation, then the birds are not getting yolk color other than from their feed because exercise and outdoor access does not affect yolk pigmentation. Birds kept in the same outdoor pen all year will soon eliminate most vegetation, which also is dormant during winter, so color intake may vary throughout the year. What does this tell you about egg pigmentation from pastured hens, where there is no “pasture”?
Yolk color does not mean the birds are organic. The intensity doesn’t mean they get more sunlight. It’s not really breed‐related either. Bugs and worms have no effect on yolk color. And it surprises a lot of people when they learn that yolk color has about zero effect on nutrition. However, some eggs with intensified yolk color will certainly add more lutein and omega 3 fats to your diet if the birds were given specialty diets with these ingredients. Lutein helps night vision which diminishes with age, and the omega 3 fats influence heart health. Some consumers claim yolk color to be a taste criterion, but most data shows this not to be true. Or they claim that the darker eggs came from healthier hens although bird health is not connected to darker yolks. Store‐ bought eggs may have just as intensely colored yolks as the eggs from small flocks. Egg freshness is not related to intensity, either. However, if you allow an egg to sit in a cooler for many weeks, the freshness will decrease
as expected, but the yolk color may actually get darker! This is because the proteins in the yolk are settling out, allowing the pigments to appear darker.
So, what is the intensity of the yolk color from your eggs? Well, you can run a bunch of expensive chemical tests or use digital methods and find out more than you want to know. Or you can simply use a yolk color wheel (pictured) and compare them by eye!
Yolk color wheels or fans can be found in specialty poultry equipment catalogs, hatchery suppliers, and many sites on the internet. All you need to do is crack open an egg, then compare it to the wheel. The wheel has each intensity numbered so you can easily determine yolk color intensity. It’s easy and reliable and the wheel lasts almost forever if you keep it stored folded up and away from light.