Americans eggs tend to have bright yellow yolks, because of what they feed feed the hens. Egg yolk color is almost entirely influenced by its diet. If you feed yellow corn it shows and if you feed birds white corn, the egg yolks are more white. In South America, hens that peck at red annatto seeds lay eggs with yolks ranging from pink to orange to deep reddish.
The yellow color in egg yolks, as well yellowish chicken skin and
fat, comes from pigments found in plants.
In most parts of the world, diners prefer their yolks with a bit
more color so commercial feeds often contain lutein as an additive,
although yellow maize, soybeans, carrots, and alfafa powder will
also add the color.
Many egg eaters assume that darker yolks are a sign of higher
nutritional value. That is not true. Although chicken feed does
influence the nutritional value of birds and their eggs, researchers
say yolk color does not tell you anything about nutritional value. When
it comes to taste, slap a few eggs next to a huge hunk of bacon and
the taste becomes awesome, regardless of yolk color.