What causes bad egg pores

[Poultrybonkers]

Not my photo but most of my eggs look like this....

What causes it? I read somewhere most don't hatch either. Why do they keep laying them? Should I cull ones that are laying them?

 

[Chicken Egg 17]

My one layed an eggs like that and they all hatched but one or two out of 10

 

[donrae]

My understanding is it's a lack of calcium. What are you feeding your birds, how old are they and what breeds?

My red sex links consistently had thin shelled eggs after the first laying cycle. Didn't seem to matter what I fed them. They still laid great, large brown eggs, but the shells were brittle like that.