“…In mares, embryo size is radically influenced by the PO day selected to implement its recovery (Betteridge et al, 1982;Hochi et al, 1995;Eldridge-Panuska et al, 2005;Choi et al, 2010;McCue et al, 2010;Díaz et al, 2016;Guignot et al, 2016;Wilsher et al, 2019). For the most part, if the embryo is collected either during the sixth or sixth and a half PO day, it is typically ≤ 300 µmØ (Iuliano et al, 1985;Freeman et al, 1991;Eldridge-Panuska et al, 2005;Hudson et al, 2006;Choi et al, 2010;Guignot et al, 2015;Pérez-Marín et al, 2017;Pérez-Marín et al, 2018;Silva et al, 2018).…”