Received: 18 July 2019
Accepted: 25 November 2019
First Online: 7 January 2020
Ethics approval and consent to participate
: During the entire experiment, all animals received humane care in compliance with good animal practice according to the animal ethics procedures and guidelines of China and its owners also agreed to collect samples. The procedure of sample collection was approved by the Animal Experiment Committee of Henan Academy of Agricultural Sciences (Approval number SYXK 2014–0007).
: The authors declare that they have no competing interests.