Received: 10 October 2017
Accepted: 30 January 2018
First Online: 29 March 2018
Compliance with Ethics Standards
: The authors declare that they have no competing interests.
: All animal experimental procedures have been reviewed and approved by the Animal Care and Use Committee of Sinovet (Jiangsu) Biotechnology Co. Ltd. (approval ID: SYXK(Su) 2013-0032). All pigs were supplied with water, food, and healthcare throughout the study period.