Our family keeps few laying hens. These are mainly just for us to have some eggs, and because we like watching the chickens scratch around the barnyard. When I have an extra dozen, I take them to the office and give them away. More often than not, my co-workers are surpised to see that the eggs are not white-shelled, but instead are brown.
Here in the United States, almost all the eggs sold are white. You've probably seen brown eggs now and again, perhaps at your local grocery store or more likely at the food co-op or the farmer's market, but mostly you've seen white. You may have even wondered why this is and what the differences are. I have an answer or two.
What are the differences?
The color of the shell. That's it. Nutritionally, there is no difference between chicken eggs from different colored shells. Once they shell is cracked and the egg is in the mixing bowl or the frying pan there is no difference.
What determines the shell color?
The color of the shell is determined by the breed of the chicken. Rhode Island Reds and Buff Orpingtons lay brown eggs. Blue Andalusian eggs are white, and Araucanas lay eggs that are green.
Why does my local supermarket only have white eggs?
Most eggs that make their way to market come from corporate agriculture. And the corporations have found that the most efficient egg-laying breed is the White Leghorn. And the White Leghorn lays, you guessed it, a white egg. That's why you'll sometimes see folks who are backers of biodiversity tell you to buy brown eggs. A brown egg did not come from a White Leghorn, but from some other breed. And often eggs from free range chickens or organic eggs are brown because the farmers who raise animals this way often are also interested in breed diversity.
So buy your white or brown, buy them from a local farmer or from Fred Meyer. You may make a political statement one way or the the other, but they'll taste the same. Better yet, just raise a chicken or three yourself. Fresh eggs are just hard to beat.
http://www.mcmurrayhatchery.com/
http://www.epicurious.com/run/fooddictionary/browse?entry_id=8040
http://www.metroactive.com/papers/sonoma/01.23.97/news-9704.html
http://www.sciencenews.org/sn_arc97/10_4_97/bob1.htm