Funding for this research was provided by:
the National Natural Science Foundation of China (31372431)
Hunan Agricultural University (15YJ05)
Received: 10 August 2017
Accepted: 24 January 2018
First Online: 8 February 2018
Ethics approval and consent to participate
: All procedures involving animals in the present study were approved and overseen by the Hunan Agricultural University Institutional Animal Care and Use Committee (No. 43321503).
: Not applicable.
: The authors declare that they have no competing interests.
: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.