Short answer
Yolk colour mainly reflects carotenoid pigments in the hen’s feed. Maize, green plants and permitted pigment-rich ingredients can deepen the colour without necessarily changing welfare or overall nutritional quality.
Pigments move from feed to yolk
Hens absorb yellow, orange and red carotenoids from their diet and deposit them in developing yolks. The mix of ingredients determines both intensity and shade. A pale yolk may simply reflect a feed containing fewer visible pigments.
Dark does not automatically mean pasture-raised
Outdoor access may expose hens to pigment-rich plants and insects, but formulated indoor feed can create an equally dark yolk. Producers can select feed ingredients specifically for a preferred colour. Visual appearance alone cannot verify a production system.
Nutrition may vary independently
Feed can also alter specific nutrients such as omega-3 or vitamin D, but yolk colour is not a direct measurement of those nutrients. Use quantified nutrition claims and credible welfare certification rather than treating orange colour as proof.