You've probably noticed that chickens have eggs with different colored shells, haven't you? Some people believe that brown eggs are more nutritious than eggs with a white shell. Is this information true?
The eggshell is rich in calcium carbonate and acts as a chamber for embryo development.. Although many people believe that their color is related to the animal's diet, this is not quite true.
The pigments that color the shells, hemoglobin or bilirubin, are released into the walls of the oviduct. The color of the shell, which can be white, brown, red, green and even shades of blue, is related to the breed of the chicken. Mediterranean chickens, such as the Leghorn, lay egg whites; American and Asian hens, such as New Hampshire, lay eggs in shades of brown. It is clear, therefore, that this trait is genetically determined and there is no way food can have an effect on it.
Many people say that the color of the feathers is directly related to the color of the egg shells. However, sometimes there are white animals with dark colored eggs and vice versa. It is worth noting that some chicken breeds are capable of laying eggs with different skin tones.
Egg shell color is a genetically determined characteristic
Some people claim that by looking at the ear discs of chickens, you can get an idea of what color the egg will be. Chickens that have a white disc lay white eggs, and those that have a reddish ear disc lay eggs with a reddish shell. However, this rule is not always valid.
It is important to emphasize that, regardless of the color of the shell, eggs have basically the same nutritional value. Thus, there is no difference in the acquisition of one or the other egg, only in terms of price.
Unlike the color of the shell, the color of the yolk is directly related to the hen's diet. Chickens that eat more corn, for example, have eggs with a more reddish yolk. This occurs thanks to deposition of carotenoids (reddish colored pigments) from ingested food.
It is for this reason that egg yolks from farm hens are less reddish than those from free-range hens. Farm chickens are usually fed products that have few nutrients that provide pigment.
By Ma. Vanessa dos Santos
