EFFECTS OF OOCYTE MATURATION LENGTH, SPERM CAPACITATION TIME, AND HEPARIN ON BOVINE EMBRYO DEVELOPMENT

This study examined the effects of extending oocyte maturation 4 h bey ond current methods and capacitating sperm with or without heparin 4 h before oocyte introduction to determine whether embryo development wo uld increase after in vitro fertilization. Oocytes were aspirated from ovaries that were collected at slaughter. Cumulus-enclosed oocytes we re matured in M-199 supplemented with serum from cows in standing estr us (20%), antibiotic-antimycotic solution (1%), HEPES (10 mM), and equ ine LH (30 mu g/ml) in a humidified 5% CO2 atmosphere. Oocytes were ma tured for either 24 or 28 h and subsequently fertilized with sperm tha t had been capacitated 0 or 4 h (before oocyte contact) with or withou t heparin (0.2 mu g/ml). Data were analyzed as a 2 x 2 x 2 factorial d esign. Percentages of cleavage and development were transformed by the arcsin square root method before analysis of variance. An interaction of maturation length and sperm capacitation resulted because cleavage rate decreased with precapacitated sperm, but only within the 24-h ma turation period. Heparin increased cleavage rate at 48 h alter fertili zation but did not affect further development. More oocytes developed to morulae when they matured for 24 h than when they matured for 28 h. In conclusion, a 24-h maturation length without precapacitated sperm was optimal for the subsequent development of cumulus-oocyte complexes .