We have had multiple chickens lay soft or shell-less eggs lately. We have two flocks (2 years old and 10 months old) and hens from both flocks have had issues with this in the last several weeks or so. We were feeding them all flock feed with calcium on the side but switched back to a layer feed about a week or so ago. We still make oyster shells available at all times and we also crush up dried egg shells in their snacks on occasion. Today we had another hen lay a soft egg. How long does it take to have the new layer feed make a difference? What else can we do to correct this issue?