2.1 Ethics statement
This study was conducted according to the animal welfare guidelines of
the World Organization for Animal Health, and animal sampling was
carried out in strict accordance with guidelines established by the
Ethics of Animal Experiments of Northwest A&F University, Yangling,
China. All the protocols were approved by this committee (Permit Number:
2014BAD23B11). The field study did not involve endangered or protected
species. No specific permissions were required for the collection of
samples because the samples were collected from public areas or
non-protected areas.