Small farms probably aren't deliberately pumping beta carotene into their hens, and battery farms don't fortify their feed to change yolk color. Strikes me as similar to the situation with factory tomatoes, which are gassed to appear ripe.
Sure they do. Read up on research for chicken food - they are careful to add enough beta carotene to give the yolks a good color, and more expensive eggs add extra.
The research for chicken food is amazingly thorough.
The gas on a tomato really does ripen it, it's not just appearance (although that doesn't necessarily help the taste).
You actually don't want to pick a tomato when it's red (ripe), the best is to pick them just at the start of the ripening process (a hint of red), then put them in sunlight to let them finish, the taste and texture is much better because it doesn't get diluted with extra water if you left it on the plant (and also avoids the risk of the skin splitting).
With some plants they bred the ability to self ripen out of them, so ethylene gas is required. But I'm not sure if that was done to tomatoes.
I have never seen a supermarket egg with a dark orange yolk. When we first started getting farm eggs, I worried there was something wrong with them, was how jarring the difference is.
As for tomatoes, yes, that was my point: supermarket tomato color is the product of manipulation. Color is a necessary but insufficient indicator of quality. (I'm not saying there aren't good supermarket tomatoes, if you buy them at a sane time of year).
You suggest that battery farms are boosting beta carotene to alter the color of egg yolks. Ok, I believe you. What I'm saying is that I doubt that the family in Michigan who sells us dirty chicken eggs in the summer is manipulating the beta carotene content of their feed to market their eggs; they don't do anything to market their eggs at all. Whatever they're eating, it's (a) naturally high in beta carotene and (b) sharply different from what battery hens eat.
