Pluripotency exists during early mouse development but transiently. This short period is further dissected into three phases such as “naïve”, “formative” and “primed”. In mice, cells in the naïve state is equivalent to pre-implantation epiblast cells as well as embryonic stem cells. Formative phase starts after implantation and ends at the onset of gastrulation and recently captured as formative stem (FS) cells. Primed cells are gastrulating cells, which still have the plasticity in the embryo and its in vitro counterpart is EpiSCs. ES cells are known to differentiate into any linages however they don’t respond to differentiation signals directly. EpiSCs are known to lose germ cell competency. FS cells have direct differentiation potency into all three germ layer cell types and germline cells. FS cells are capable of making blastocyst chimaera. These three states have different growth factor signal requirements, gene regulatory network and chromatin landscapes. Most recently, we established the pluripotent stem cell lines from livestock species (pig, sheep and cow) and they were termed as Embryonic Disc Stem Cells (EDSCs). EDSCs and large animals have a potential to study human development and diseases to replace rodent model. I want to discuss about why formative pluripotency is important and how large animals can be a useful alternative model.