IB infections in breeders can damage the oviduct. Especially when infections are occurring in the first week(s) of the life of the birds, this can result in false layers, birds that look normal with all the signs of a laying bird, but without producing the eggs.
The problem with a very early infection is that it damages the oviduct in such a way that the oviduct can get blocked for egg passage. The birds develop normal throughout the rearing period and when the light stimulation is done, their hormonal system reacts and they show all the normal signs for egg laying like a coloured comb, space between the leg bones, development of follicles on the ovary etc.
However, when the follicles are released from the ovary to be tranformed into an egg, the yolk cannot pass the oviduct. As in the oviduct fluid is released to form the albumen, the fluid accumulates in the oviduct, as the egg yolk in the oviduct continuous to signal the system for releasing the fluid to form the albumen.
This results in a massive accumulation of fluid in the oviduct, up to 1 liter or even much more. As the oviduct is blocked, the fluid will not be released towards the cloaca and will accumulate. The birds eventually die from this massive build up of fluid, and when a post mortem is performed it at first looks as a severe case of ascites because of the amount of fluid in the body cavity, and only after further examination it will show that the fluid is located in the oviduct.
Before the birds die, they show a very typical way of walking, as they have to move their legs around an enormous belly filled with water. This "pinguin" walk is a clear signal, and when these birds are examined palpation of the belly will quickly indicate the unusual presense of fluid.
The problem with this early IB infection is that the negative effects show in production. If the problem is caused by a mistake in the program, it can mean that there is another 25-30 weeks of flocks in the pipeline, as changing of the program will be too late for the flocks that are already in rearing. And as the percentage of birds that is affected can be sometimes high, this can become a very costly time period.
It is therefore important to be very alert on the occurance of false layers. The problem doesnt happen very often, but if it does happen, a careful analysis of the cause should be executed, focussing on the protection of the flocks against IB in the very first period of their life.