how much calciun does hens need to lay egg

Layer feed should have enough calcium for them. Most people recommend to have layer food available freely and have some crushed oyster shell available at all times in a separate bowl so the chickens can 'supplement' as they need. I have layer food in the coop, the girls run loose in the yard during the day (as long as we don't have snow....) for 8-9 hrs and eat bugs and weeds but also eat their layer feed. I also keep a small bowl of grit available.

 

My birds produce nice thick shells with just layer feed. I do supplement oyster shell in the fall and winter when they have been laying a while. I read that they will lose bone calcium during the laying season and replenish it during the winter break. I want to ensure plenty is available.