Funding for this research was provided by:
the earmarked fund for the China Agriculture Research System (CARS-42)
the science and technology innovation project of the Chinese Academy of Agricultural Sciences (CXGC-IAS-09)
Received: 22 July 2020
Accepted: 18 June 2021
First Online: 30 June 2021
: All experimental procedures with ducks were performed according to the Guidelines for Experimental Animals established by the Ministry of Science and Technology (Beijing, China). Ethical approval on animal survival was given by the animal ethics committee of the Institute of Animal Sciences (IAS), Chinese Academy of Agricultural Sciences (CAAS, Beijing, China) with the following reference number: IASCAAS-2019–19.
: Not applicable.
: All authors declare that they have no conflict of interests.