Funding for this research was provided by:
Bộ Giáo dục và Ðào tạo
Received: 5 November 2019
Accepted: 29 April 2020
First Online: 6 May 2020
Ethics approval and consent to participate
: All procedures involving in this study were vetted by the Vietnam International Education Department Fellowship, Ministry of Education and Training, Vietnam (911 Research Project Grant Scheme) in compliance to the recommendations of the Guide for the Care and Use of Agricultural Animals in Research and Teaching (2010) [CitationRef removed], since North Vietnam does not impose ethics on the use of local animals for research. Informed consent form (field studies and sampling) was filled by the farmers whom are owners or managers of the farms that participated in the study.
: Not applicable.
: The authors declare that they have no competing interests.