It's to do with diet. IIRC, some farmers feed their flock flax in order to get more orange yolks. But free range hens that have access to insects tend to have

It's to do with diet. IIRC, some farmers feed their flock flax in order to get more orange yolks. But free range hens that have access to insects tend to have a nicer flavour in my experience. Generally speaking, an egg with a hard shell and a very bright yolk will be nicer and that tends to correspond with free range hens. But, climate where you live will influence how realistic that is.