Effects of essential and non-essential amino acids on in-vitro maturation, fertilization and development of immature bovine oocytes

Background: Addition of amino acids to the culture medium is beneficial for embryonic development in many species. Objective: The objective of this study was to investigate the effects of amino acids on the in vitro maturation and embryonic development of the bovine oocyte. Materials and Methods: Bovine ovaries were collected from a local abattoir and brought into laboratory. Cumulus-oocyte complexes (COCs; n=1212) were aspirated from follicles (2-8 mm in diameter) and randomly assigned to four groups for maturation in culture: (1) Basic medium alone as control; (2) Basic medium supplemented with 2% MEM essential amino acids solution; (3) Basic medium supplemented with 1% MEM non-essential amino acids solution; and (4) Basic medium supplemented with 2% MEM essential amino acids solution + 1% MEM non-essential amino acids solution. COCs were incubated in 1 ml maturation medium in an Organ culture dish at 38.5°C in an atmosphere of 5% CO2 with high humidity. After 24 h of culture, 372 oocytes were fixed to determine maturation rate and the remaining oocytes were used for in vitro fertilization (IVF). Following 18 h of insemination, 437 oocytes were fixed and examined for fertilization and 403 oocytes were further cultured. Results: There were no differences in maturation rates and penetration rates among the four groups. Although oocyte cleavage rates were not different in the four groups, embryo development up to the 8-cell stage and blastocyst were significantly higher (p<0.05) in Group (2) and (4) than in the Control and Group (3). Conclusion: These results indicate that the presence of amino acids, especially essential amino acids in the maturation medium is beneficial to oocyte cytoplasmic maturation and subsequent early embryo development in vitro.