ABSTRACT
This study investigates the impact of eugenol (EU) supplementation on bovine oocyte in vitro maturation (IVM) and antioxidant capacity, as well as in vitro embryo production and quality after conventional in vitro fertilization (IVF). A total of 1077 cumulus oocyte complexes were cultured in TCM-199+ without EU supplementation (control treatment) or supplemented with EU at the concentrations of 10 µM (EU-10), 20 µM (EU-20), or 40 µM (EU-40). After IVM, the oocytes were subjected to IVF and embryo culture. The addition of EU at 40 µM to the IVM medium improved (P < 0.05) the antioxidant capacity and cleavage rate when compared to the control treatment. Moreover, a positive correlation (r = 0.61, P < 0.03) was observed between cleavage rate and EU concentration. The addition of EU at concentrations of 10 and 20 µM decreased (P < 0.05) the calreticulin (CALR) levels in expanded blastocysts when compared to the control treatment and EU-40 treatment. However, the EU-10 and EU-20 treatments had a greater (P < 0.05) mean total cell number (TCN) per expanded blastocyst when compared to the control treatment and EU-40 treatment. In conclusion, the addition of EU to the enriched culture medium during IVM of bovine oocytes improved the antioxidant capacity of the spent medium, as well as the cleavage rate and embryonic quality (i.e., TCN/expanded blastocyst), and reduced the endoplasmic reticulum stress (i.e., CALR levels) in the embryos. Thus, we recommend enriching the IVM medium with 10 µM EU for in vitro bovine embryo production.