The first time I contemplated the meaning of "grass-fed chicken" was last year in a restaurant when I saw it on the menu. I had to laugh at the thought of chickens trying to clip grass with their beaks and eat it. I just couldn't picture it. I thought it was a typo on the menu. So I had to research this. If you are already shaking your head at me, it's because you can tell that I am a curious bird who wasn't raised on a farm.
Off to the farm I go! I had a little nervous laughter going into my question to a farmer who raises pasture-fed chickens. "So, do they really eat grass?" I asked. He said, "Yes they do, but they really like the bugs and worms they find in the grass. That along with being in direct sunlight gives the chicken and eggs the most nutrition which makes for that wonderful deep golden color in the yolks. It's nothing like the pale yellow yolks you find from most eggs."
Aha! This is true of most whole foods. They are richest in nutrients when they are most vibrant in color. Think of a red ripe tomato in-season. It delivers great nutrition and taste, while an out-of-season pale red tomato is a whole different story... and a sad one at that.
Chicken are omnivores and they like to walk around. It's amazing how when you let them do what they were made to do, they are the healthiest, and they pass it on. Like one of my friends told her kids, "Happy chickens make happy people!"
Their eggs are a great source of Vitamins A and D and they contain a balance of omega-3 and omega-6 fatty acids (DHA) which is important for nerve functioning and brain development. In the modern American diet of processed foods and factory farming, we usually get way too many omega-6's and not enough omega-3's. We need a balance of both.
Here's the research:
People need sufficient amounts of dietary omega 6 and omega 3 fats and they need to be balanced for normal development. Range fed eggs have an omega-6 to omega -3 ratio of 1.5 to one whereas the "supermarket egg"has a ratio of 20 to one. Modern agriculture's emphasis on increased production has led to the development of chicken feed that is being reflected in the out-of-balance ratio of fatty acids in the "supermarket egg." http://www.mercola.com/beef/health_benefits.htm
People with a diet rich in omega-3s are less likely to suffer from depression, schizophrenia, attention deficit disorder (hyperactivity), or Alzheimer's disease. Omega-3s are most abundant in seafood and certain nuts and seeds such as flaxseeds and walnuts, but they are also found in animals raised on pasture. The reason is simple. Omega-3s are formed in the chloroplasts of green leaves and algae. Sixty percent of the fatty acids in grass are omega-3s. When chickens are housed indoors and deprived of greens, their meat and eggs also become artificially low in omega-3s. Eggs from pastured hens can contain as much as 10 times more omega-3s than eggs from factory hens. http://www.eatwild.com/healthbenefits.htm