In vitro maturation (IVM) of equine oocytes results in a reduced developmental capacity compared to in vivo matured oocytes. Cumulus cells mirror oocytal well-being through close bidirectional communication. After maturation, the cumulus complex is not required anymore. Therefore, these cells are a unique noninvasive source to investigate metabolism during this crucial developmental phase. This study analyzed the “Cumulome” (metabolome and proteome of cumulus cells) with different developmental potential: Not matured (NM; n=18), Cleaved (CL; n=15) and Blastocyst (BL; n=19).