over the last two decades old bird
diseases, such as Coryza, Blackhead and Pasteurelle multocida increasingly reared their ugly heads among
free-range hens. These diseases barely occurred when laying hens were kept in cages.
Addressing the growth in demand for animal friendly housing systems, more and more birds are kept in free-range houses and less of them spend their days in cages. Dr Naomi de Bruijn, poultry veterinarian at GD Animal Health in the Netherlands, analysed reports on the prevalence of several poultry diseases within the Dutch borders. “What stood out were the statistics of old poultry diseases that almost didn’t appear anymore. We noticed a rise in occurrence, as a result of the switch to free-range housing systems.”