That was quick! Reader Sue asks: why do some eggs have darker yolks than others, and does a deep yellow color mean the yolks are more nutritious?
As far as I know a deep yellow yolk isn’t necessarily more nutritious than a pale yellow yolk. However I do know what makes one yolk darker than another: the diet of the hen. Chickens are omnivorous scavengers, which means they’ll eat all different sorts of things…pretty much whatever they come across. Hens that “scratch” in the barnyard (or the suburban back yard, as the case may be) eat everything from grains and legumes to grasses, leaves, roots, insects, worms, mice…even the carcasses of dead animals.
On commercial farms chickens eat a grain feed made up of things like corn, rice, soybeans and peanuts. But that diet, unless it’s especially rich in corn, won’t necessarily deliver eggs with deep yellow yolks, which consumers definitely prefer. Alfalfa is something poultry farmers will sometimes add to chicken feed to enhance yolk color. Marigold petals are another, though as far as I understand it, they’re considered a “cheat” in agricultural circles. Why I don’t know. Possibly because they’re cheap!