To increase the productivity of in vitro development, the antioxidants have been used for culture system of bovine oocytes and embryos. However, comparative studies on these molecules are rare and direct beneficial effects on blastocyst production cannot be discriminated for best results. The study was conducted to determine the influence of N-acetyl-L-cysteine (NAC), N-acetyl-L-cysteine amide (NACA), glutathione (GSH) and cysteamime (CYS) on maturation competence of COCs from GV to MII stage and productivity of blastocyst formation during in vitro fertilization and culture. There was no difference among maturation rates of oocytes to metaphase II with polar body with antioxidants for any of the treatment groups (p>0.05). However, the significant improvement on the rate of blastocysts (32.3±5.0%) was found in 0.1 mM CYS treatment than 0.3 mM NAC, 0.2 mM NACA or 0.5mM GSH (p<0.05). The addition of NAC (18.8±3.7%) or NACA (21.2±3.9%) did not improve development competence to morula and blastocysts than control (24.4±4.1%) and GSH (26.5±5.0%) (p>0.05). Our study showed that medium supplementation with CYS during IVM and IVC improved the rate of bovine embryo development but not with NAC, NACA and GSH addition.

During the oocyte maturation, antioxidants may be beneficial for futher developmental competence against reactive oxygen species (ROS) because the media for oocytes lack boiomolecules that serve as scavengers. In this study, N-acetyl-L-cysteine (NAC), N-acetyl-L-cysteine amide (NACA), glutathione (GSH) and cysteamime were compared to determine the effects of protection for ROS from GV to MII stage when supplemented during in vitro maturation (IVM) and in vitro culture (IVC) of bovine oocytes. NAC is one of well known ROS scavanger and NACA is modified form of NAC to help permeation into cytosolic area of oocytes. Significant improvement on the development undergoing blastocysts (32%, vs 18%, 22%) were found when cysteamine (0.1mM) was added to the maturation medium than NAC (0.3 mM), NACA (0.2mM) or GSH (0.5 mM) as compared to control medium with antioxydents. However, the addition of NAC(18%) or NACA(21%) to media did not improve the proportion of oocytes undergoing development to morula and blastocysts than control (24%) and GSH (26%). Our study showed that medium supplementation with cysteame during IVM and in vitro culture (IVC) improved the rate of bovine embryo development, in contrast to extracellular antioxidants like NAC, NACA and GSH that caused no improvement.