And I bet if there is a yellow or gold egg it's from adding tumeric to the feed so yes all natural!! gold more tumeric yellow less
My chickens have been eating turmeric (mixed into their feed) since 2009 with no change in the egg shell color. If I feed them larger amounts, it wouldn't be cost effective. So, while it could be the herring, or maybe salmon, where the plankton they eat is actually that dark melon color, they're not going to be able to use turmeric. A more scientific method of getting yellow/gold eggs will have to be employed so that prices of the feed will be low enough for people to buy it.
Also, a real feed additive, marigolds, does make the yolk darker orangey/yellow, but doesn't change the shell color. I can't wait for tomorrow to find out from the feed company how they're going to do it. I bet it's patented, though, or a secret, like KFC, where the feed company doesn't legally don't have to tell the recipe. Plus, if the ingredient is added in a low enough amount, it doesn't have to be listed ... like Senomyx (or at least it used to be like that).
Oh, but farmed salmon does get its color from something added to the feed. That colorizing feed additive for salmon must be cheap-ish or farmed salmon would be priced out of the market.
But attimus with his/her red herring idea. That's genius.