[Serologic monitoring of pullet and laying hen flocks in Switzerland: results from the years 1990 and 1991].

In 1990 and 1991 4522 blood samples from 398 pullet flocks and 1338 blood samples from 128 laying flocks were monitored for antibody against infectious bronchitis virus, infectious laryngotracheitis virus, adenovirus, reovirus, infectious bursal disease virus, Newcastle disease virus, Mycoplasma gallisepticum and Mycoplasma synoviae. The results are… (More)