ACKNOWLEDGEMENTS
We are very grateful to Mr. Changyu Ma (Henan Xurui duck industry Co.
Ltd) for kindly providing the healthy duck embryos and the epidemic
information. This work was supported by the grants from Key Scientific
Research Foundation of the Higher Education Institutions of Henan
Province (19B230010), Scientific Innovation Fund of Henan University of
Animal Husbandry and Economy (XKYCXJJ2020011), Youth Science Foundations
of Henan University of Animal Husbandry and Economy (2021HNUAHEDF004)
and Scientific Innovation Team Project of Henan University of Animal
Husbandry and Economy (2018KYTD13).