I live in Oregon, and we've had a VERY long spell without sun (changing tomorrow, though). Do chickens take Vit D in from the sun? If they do, and it's not sunny, would that cause reduced calcium uptake (they have many sources of such: pellets, oyster shell, egg shells, greens), which would result in soft shelled eggs? I have a HUGE problem with it right now. Anybody else live around here having soft-shelled egg issues?