Funding for this research was provided by:
National Natural Science Foundation of China (31401055)
Shandong Province Agricultural Animal Breeding Project of China (2013LZ02-015)
Shandong Province Modern Pig Technology and Industry System Project (SDAIT-06-022-03)
Shandong Province Weifang city science and Technology Bureau Project of China (201301153)
Shandong university of science and technology project (J16LE58)