The Exact Difference Between White And Brown Eggs
You may have heard whispers that brown eggs are somehow better than white ones — it's often said that brown eggs are fresher, or a better source of nutrients (among other supposed advantages). However, the rumors about brown eggs' superiority are just that, rumors. The truth is that beyond the color of the shell, there's no functional difference between what you get inside a white egg and a brown one.
The color does, however, offer some indication of which breeds of chicken may have laid the eggs. Accordign tot the USDA, white eggs come from breeds such as Leghorn, Cornish, or White Rock hens while Rhode Island Red, New Hampshire, and Plymouth chickens lay eggs with brown shells. Interestingly there are breeds of chicken that lay blue or blue-green eggs, as well, which are the Araucuna chicken, from South America, and Dongxiang chickens from China, although the eggs still taste the same as the more common egg colors (with some variation, depending on a chicken's diet and the egg's freshness).
What other factors cause eggs to vary in color?
Although a chicken's breed (and genetics — the nature end of the spectrum) is the main factor in determining what color its eggs will be, there are other smaller influences on egg color. For example, hens that lay brown eggs will tend to lay lighter-colored eggs as they get older (although they're still brown — just a lighter shade). This is because older hens lay larger eggs, so the pigment that colors the eggs will be spread more thinly over the larger surface area.
Chickens that lay brown eggs will also start laying lighter-colored eggs when they're stressed out from, say, loud noises or being cooped up with too many other chickens (the nurture side of things). This is due to hormones that are released when chickens feel nervous or scared. While some sources claim that egg colors depend on a chicken's feathers, with white eggs coming from white hens, and brown eggs from brown ones, this assertion seems to be little more than barnyard hooey.
So why do brown eggs sometimes cost more?
The idea that brown eggs are better than white ones may be connected to the fact that they tend to be more expensive. But egg quality isn't the reason for the price tag difference — it's that brown eggs require more energy to produce. While white eggs are simply formed inside the chicken's uterus and then laid, brown eggs undergo a pigmentation process. But for these chickens to make that pigment, they need more energy, and that means more food. That's an additional cost for the farmer, resulting in a higher price tag at the grocery store.
In fact, white eggs used to dominate the market in the U.S., but clever marketing (such as a campaign arguing that "brown eggs are local eggs" and therefore, more fresh) helped to boost the idea that brown eggs are the better-tasting or more nutritious egg. Of course, brown and white eggs can taste different to each other, but it's not the shell color that affects the quality. Rather, it's the freshness of the eggs, the chicken's diet, and the environment in which it's raised that determine how tasty and healthy it can be.