Help with hens who aren't laying as much and have very weak shells

[BethKg]

Hello. I'm new to this group. Does anyone know why my hens would almost stop laying and when they do lay, the shells are thin or not there at all. They are all only 2 years old. I have always had oyster shell in their coup, their feed has calcium in it too. I have 3 hens and a rooster. All barred rock.
They stay in their coup at night but I let them free range all day. They put themselves away at night. I'm afraid they have a disease. Although they all act healthy. Does anyone have any ideas?

 

[Pork Pie]

Hi Beth and welcome to BYC. There could be a number of causes of the issues you observe. This link may help - http://www.backyardchickens.com/a/common-egg-quality-problems

 

[Kiki]

Welcome to BYC.
What exact feed to you use and have you ever dewormed them?

 

[aart]

What exact feed to you use

.....and any other foods or 'treats'.

How long have they been laying thin shelled eggs?
If you live in the Northern Hemisphere, they could be ramping down production getting ready to molt. Can get some funky eggs around molting time.

Oh, and...Welcome to BYC! @BethKg
Where in this world are you located?
Climate, and time of year, is almost always a factor.
Please add your general geographical location to your profile.
It's easy to do, (laptop version shown), then it's always there!