Posted by Theresa
(Mpls., Mn) on 07/25/2015
Can you think of anything that has changed in your girl's routine? It is one thing for a single hen to have this affliction, but the entire flock? Consider if this really is just one afflicted hen vs the whole coop.
Stress - hen pecked or harried by the cock - could cause this in one bird, and also that one bird having a problematic metabolism. For the entire flock to be affected you might consider contaminants or the water; saline water and poor nutrition can cause thin shelled eggs, as well as disturbances during the egg laying process - got a coon or fox trying to enter the hen house?
It sounds like you are savvy on their nutrition, but it never hurts to reassess your feed protocol:
"Causes for thin egg shells
Calcium is the primary mineral that makes up eggshells and when not supplied in the diet, the hen does not have the basic materials needed to make the shell. The problem is produced when whole grains or feeds deficient in minerals and vitamins make up the bulk of the laying hen diet. Thin egg shells are observed when calcium, phosphorus and vitamin D3 are not provided in diets at adequate levels. It is more often observed during periods of hot weather because calcium is conserved and retained within the hen's body less efficiently.
The quality of the shells is improved by feeding a complete laying ration as the only diet. This diet supplies all nutrients in the proper proportions so the hen can produce good shells. If thin egg shells becomes a problem, it is advisable to add 2 pounds of oyster shells (as an oyster shell flour or hen-sized oyster shells) to every 100 pounds of complete layer ration.
This will provide a quick remedy to the problem and should restore egg shell quality within a short period of time. After the egg shell quality is restored, the addition of oyster shell can be eliminated and the complete layer diet can then maintain good egg shell formation. It is also advisable to also add a vitamin supplement to the drinking water while the oyster shell is being added to the feed. This will help ensure that calcium and phosphorus in the diet is being properly absorbed through the digestive system and will be available for deposition as shell on the egg."