In broiler breeder production we sometimes find eggs that are not completely "round", but have one or more flat sides, without obvious damages. They are noticed when you check the eggs from above, or when you take them between your fingers. If you roll them over a flat service it is obvious that they are not round, as they are "bumping".
The cause for these kind of eggs might be a very early (first days/week) infection with a virulent IB strain. This can damage the oviduct in such a way that the egg will not roll through the oviduct when its formed, causing this kind of malformation. Other signs of such an infection can be poor production, more poor egg shells (although the other eggs are normal) egg peritonitis, fluid in the oviduct, false layers and in-active ovaria, as they are all caused by the damaging effect of this early infection. As the effect is seen during production, it is sometimes difficult to relate it back to what happened in the first weeks of life. A cure is not available, prevention can be done by a good protection through vaccination at the hatchery or arrival. Selection and culling of the infected birds is not very easy as they can be difficult to recognize, the combs usually often have a normal appearance.