What is a Chicken Egg?
A chicken egg is an egg laid by a chicken. In general, eggs are composed of several parts. They have a hard outer shell, which would help protect a growing bird embryo (if the egg is fertilized), and inside the shell is the ovum. The ovum is the reproductive cell or egg produced by female birds that would nurture and sustain an embryo before it was strong enough to break out of the shell and become a “fully-fledged” chicken.
In most mammals, ova that are unfertilized are periodically shed with the special lining of the uterus that would help nurture a growing fetus. Fertilized ova stay in place and become part of the building blocks that grows into an infant mammal. Chicken eggs are different in this respect. Hens lay both fertilized and unfertilized eggs, and most of the development of the chicken embryo in fertilized eggs occurs outside of the hen’s body. Special care of a fertilized chicken egg is required for this to occur.
There are two main components of the ova in chicken eggs. These are the albumen or “white” of the egg and the vitellus or egg yellow or yolk. Most people will note some thick milky white membranous structures in the egg too. When not providing nutrition for growing chickens, these eggs are a source of nutrition for people and for animals that may eat eggs. In fact, of all eggs consumed by people, chicken eggs are most common, and recipes calling for eggs tend to mean eggs from hens, unless they specify otherwise. Though there are specialty markets that sell emu, ostrich, quail and duck eggs, these remain a tiny percentage of most eggs purchased by humans.
While the chicken was once hailed as perhaps a perfect food for humans, there are some concerns about consuming too many eggs. Though a single egg isn’t tremendously high in calories, egg yolks do contain high levels of cholesterol. Some people avoid this issue by simply eating egg whites instead, which are high in protein. Others, however, don’t care for the whites eaten alone. There’s also some argument that sources of cholesterol in chicken egg yolks may actually help lower overall bad cholesterol count, though this issue is hotly debated.
Most people stick to eating the interior of the egg and either discard or compost egg shells. Actually, eggshells are edible, and some people blend them into shakes. Eggshells may also constitute part of chicken feed since they have nutritive value.
One thing that may prove confusing for people is the different grades of chicken eggs and their different sizes. Moreover, some eggs are labeled organic and others may be sold as created by free-range chickens. The country in which the eggs are produced usually regulates the definitions of each of these terms and grades. Typically a chicken egg that is free range and organic will cost most, but price is usually higher for larger eggs too, and some people purchase fertilized eggs because they’re lower in cholesterol or eggs with different colored shells.
Written by Tricia Ellis-Christensen
