INFLUENCE OF ADDING ESSENTIAL AND NON-ESSENTIAL AMINO ACIDS TO CULTURE MEDIUM ON CLEAVAGE AND BLASTOCYST FORMATION RATES OF RABBIT EMBRYOS AT 4-AND 8-CELL STAGES.

This study aimed to evaluate the effect of essential (EAAs) and non-essential (NEAAs) amino acids (AAs) at levels of 25 and 25 or 50 and 50 μl/ml, respectively, on in vitro developmental potential of rabbit embryos at 4- and 8-cell stages. Total of 12 sexual mature New Zealand White (NZW) rabbit does and 3 fertile NZW bucks were used in this study. All does and bucks were kept under similar conditions of feeding and management. Does were superovulated by eCG and GnRH (Receptal). Embryos were collected by flushing at 4 and 8-cell stages after about 32 and 40 h post- GnRH injection and mating, respectively. Embryos were in vitro cultured in TCM-199 supplemented with EAAs and NEAAs at a level of 25 (M1) or 50 (M2) μl/ml from each as compared to control (CM). Results showed slight increase in number of cleaved embryos and those reached blastocyst stage of embryos in vitro cultured at 4-cell as compared to those at 8-cell stage in spite of increasing number of embryos at 8-cell than at 4-cell stage. Cleavage and blastocyst rates were higher (P≥0.05) for embryos at 4-cell than at 8-cell stage (81.25 and 65.17% vs. 73.27 and 56.03%). Proportion of cleavage and blastocyst formation rates were higher (82.27 and 65.82%, P<0.05) in M2 than in M1 (78.67 and 60%) and CM (70.27 and 55.40%). Supplementation of M1 with AAs increased (P≥0.05) the proportion of cleavage and blastocyst formation rates as compared to CM. The effect of interaction between embryonic stage and amino acid supplementation on cleavage and blastocyst rates was not significant, reflecting the highest cleavage and blastocyst rates of embryos cultured at 4-cell stage M2 (87.17 and 71.79%). In conclusion, developmental competence of rabbit embryos at 4-cell and 8-cell stages to reach blastocyst stage was improved by supplementation of in vitro culture medium (TCM-199) with essential and non-essential amino acids at a level of 50 μl for each. [ABSTRACT FROM AUTHOR]