Abstract. In this study, the potential role of L-carnitine supplementation in the maturation of oocytes and pre-implantation development of embryos was investigated using bovine as a model. In Experiment 1, bovine oocytes recovered from the abattoir were matured in the absence (control) or presence of L-carnitine, subjected to in vitro fertilization and assessed on their developmental potential up to the blastocyst stage. The nuclear maturation and cleavage rate observed between the control and L-carnitine supplemented group ranged from 83.1% -87.1% and 57.1% -67.9%, respectively. Significantly higher blastocyst formation rate and improved total cell count in 0.1-0.5 mg/ml L-carnitine supplemented groups were observed versus the control (51.0 -54.2% vs 29.5% and 97.4 -110.1 ± 2.2 vs 82.5 ± 1.6, respectively (P<0.05). In Experiment 2, zygotes resulting from in vitro fertilization of bovine oocytes were cultured in modified synthetic oviductal fluid medium with or without L-carnitine supplementation. Results showed no significant difference on the blastocyst formation rate among treatment groups, but the total cell count of blastocyst derived from 0.1 -0.5 mg/ml L-carnitine supplemented groups were higher than the control (98.4 -115.4 ± 3.1 vs 84.6 ± 3.2, respectively (P<0.05). Overall, the results demonstrated the usefulness of the procedures utilized in the maturation, fertilization and culture of bovine oocytes and early-stage embryos. That, L-carnitine supplementation at the level of 0.1 -0.5 mg/ml concentration in the maturation and culture media tend to enhance the developmental potential of oocytes and early-stage embryos to the blastocyst stage as indicated by a higher total cell count (improved cell activity)
