Fig 1. The studied influencing factors related to excellent pig cloning.

A, donor cells derived from excellent Landrace or Large white breeding boars, B, 101–150, 151–200 or 201–250 cloned embryos transferred per surrogate, C, Day 1–5 of surrogate estrus, D, ovulation statuses including preovulation, periovulation and postovulation, and E, transfer position change or follicle puncture. Major factors including donor cell type, number of cloned embryos transferred per surrogate, surrogate estrus stage, ovulation status and embryo transfer manners were systematically investigated during excellent pig cloning.