If you notice that eggs come off the belt with rough or ‘sandpaper’ shells, this is a sign that something is happening with the birds that warrants a closer look. There are many causes, which can include a disease such as Infectious Bronchitis or ILT, improper lighting changes, water shortages, or disturbances or stress at the time a hen is due to lay that delays laying. To help uncover the cause, check eggs in the barn before egg belts are run, to determine if the problem is isolated to one area of the barn. Check the physical area and your records to figure out if there has been an event that would help explain the change in shell quality.
If your investigation leads to a suspected cause, take corrective action and observe changes. If the problem persists, contact your poultry veterinarian for further advice.