Acknowledgement
The authors would like to acknowledge the conservation farms of seven Shandong indigenous pig breeds and breeding farms of five Western commercial pig breeds for providing pig samples. We also would like to thank Editage (www. editage.cn) for English language editing. This research was supported by the Natural Science Foundations of Shandong Province (ZR2017MC043), Shandong Swine Industry Technology System Innovation (SDAIT-08-03), and Agricultural Improved Variety Engineering of Shandong (2019LZGC019).
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