Methods are provided for in vitro maturation (IVM) of bovine oocytes that include steps of (a) pre-culturing bovine germinal vesicle (GV) oocytes in the presence of C-type natriuretic peptide (CNP) and (b) subsequently culturing the oocytes of (a) for an extended duration in medium containing follicle stimulating hormone (FSH), luteinizing hormone (LH), 17β-estradiol (E2), epidermal growth factor (EGF), and fetal bovine serum (FBS).