Infectious Bronchitis (IB) is probably one of the most expensive and one of the most underestimated diseases we know in poultry, especially when we look at broiler breeders. Although IB does not cause (a lot of) mortality in adult birds, it can cause a severe drop in production and a problem in hatchability and chick quality, depending on the strains present in the flock. With an adequate vaccination program almost all damage can be prevented, but we often see that when just a standard vaccination program is used, not tailor made for the actual situation in the area and not applied with the utmost care, the protection is not as good as we would like it to see.
Obvious signs for IB infections in production are deformed egg shells, discoloured shells and "sand heads" (rough surface of the shell). Whenever a hatchery or a breeder operation is visited, take a moment to run your fingers over the eggs, to feel if the surfaces are smooth. When a flock gets older it is not abnormal to see more incidences of "sand heads", but realize that it means that the flock might be going through a subclinical infection.
Another sign of IB can be seen on the birds itself. IB infection can cause watery eyes on the birds, and this "crying" of the birds makes dust stick to the eyelids, causing a black dirty area/ring around or under the eyes. When you see that some of your birds are "crying", be aware that they will probably not be very happy. And if your birds are not happy, chances are that at the end of the day you will not be very happy as well.