Funding for this research was provided by:
Shandong Swine Industry Technology System Innovation (SDAIT-08-03)
Agricultural Science and Technology Innovation Project of SAAS (CXGC2017B02)
Youth Research Fund of SAAS (2016YQN54)
Text and Data Mining valid from 2019-12-01
Received: 6 May 2019
Accepted: 22 November 2019
First Online: 2 December 2019
Ethics approval and consent to participate
: All the animal procedures we used were reviewed and approved by the Institutional Animal Care and Use Committee of Institute of Animal Science and Veterinary Medicine, Shandong Academy of Agricultural Sciences under permit number IACC20060101.
: Not applicable.
: The authors declare that they have no competing interests.