Chicken Eggs have spots on them after a couple of days

[somhjoy]

My chicken eggs are collected twice a day and look fabulous, then within a day or two about half the eggs start to have spots on them. Chicken coop is well ventilated, cement floor with clean shavings all the time, and plenty of room outside. What is going on?

 

[Messipaw]

see if this helps http://www.the-chicken-chick.com/2012/01/how-hen-makes-egg-egg-oddities.html

 

[Kelsie2290]

Looks like what they call a mottled/ glassy shell
http://www.thepoultrysite.com/publications/1/egg-quality-handbook/23/mottled-or-glassy-shells
http://edis.ifas.ufl.edu/ps020
Quote:
"Mottled shells have pale translucent spots (sometimes called "windows") of various sizes. Such eggs appear normal when laid. The mottling develops later and may be noticeable half an hour after laying, although it is more easily detected a day later. This abnormality is inherited, although a similar effect can be induced artificially, such as when a wet, newly laid egg slides across the wire cage floor instead of rolling, or when a hen's toenail scratches the surface of a recently laid egg."

 

[somhjoy]

What can I do to correct the problem?