Honestly I don't know if there is a difference. There are probably a lot more factors to it but never believe that brown eggs, white eggs, or colored lack something that the other does not the only difference is that the pigmentation is different (that's why the color of the ear lobes exists) The only thing I can really think of is diet and freshness. When you take the egg freshness test you can use a bucket/tub of water the bigger the air cell the older it is. Diet may also be a big factor since there is not really a great feed commercially out there unless it's local. (Payback feed is not the best feed because what they do is put an enzyme in it to have the birds digest it that they originally cannot digest) What's the point of it anyways? If originally they couldn't digest it tell me again why we're feeding it to them in the first place? Picture what it'd be like to eat an egg resulting from a perfect feed that causes no harm to the chicken or has no problem digesting it.