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

ABSTRACT

Addition of amino acids to the culture medium is beneficial for embryonic development in many species. 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. 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. 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]. 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