Species appropriate diet based on how they evolved. That goes for dogs, cats, cows, horses, humans. Directly connected to health and risk factors for longevity. You are what you eat right, so feeding chickens poor quality diet for their species will devalue the nutrition of your eggs.
I think you're idea is good for pigs but chicken's don't have the right enzymes to digest such things. I have chickens so I control what they eat and control what my egg is made with. Pesticides and herbicides do get into the egg so to me, why bother having your own hens; it's much easy and...