High pathogenicity avian influenza (HPAI) is a viral disease with devastating consequences for the poultry industry worldwide. Domestic ducks are major source of HPAI viruses in many Eurasian countries. The infectivity and vary depending on host factors. To assess factors influencing ducks, we compared pathobiology two (H5N1 clade 2.3.2.1c H5N6 2.3.4.4e) 5- 25-week-old ducks. Both caused mortal...