When I use eggs I bake the shells slightly and crush/grind them to a course powder and feed them back to the hens. 2 to 3 times a week I put a bit of oyster shells in their mash. Sometimes you almost need a hammer to crack the eggs open!
I'm luck y(well, more so the chickens

) in that my DH works at a wholesale food warehouse that has produce so he bring me discards all winter. If per-chance I don't have enough, I will buy whatever is cheap at the store or cook up some carrots for them to peck at. I've also gotten some alfalfa hay. The only issue with that is because it's dry I've seen it cause crop issues. I chop it up a bit and soak it in water for a few hours. They gobble it up! The only thing I would have changed about my "winter feeding" was after a few weeks of not being able to rang, I thought after tasting one was "Needs more Bug!"
I'll try to add more animal protein next year.
All in all...if I can help it.... I will never buy "commercial" eggs again! Never did like them pale, tasteless, runny "things". Remind me of "winter tomatoes" ewww colorless, tasteless, rubbery "things"!