Defining the culture medium for the production of cattle (Bos taurus) embryos for vitrification by Cryotech method [manuscript]
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Date
2017
Authors
Alfred D. Sayson
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Abstract
The study was conducted to define a system for embryo production and cryopreservation where in it resulted in a high rate of embryo development under specified culture system that is viable for embryo transfer to recipient animals after vitrification. In Study 1, the presumptive zygotes were randomly allocated to four culture medium treatments: (1) modified synthetic oviductal fluid (m-SOF) for day 1-7; (2) pure commercial medium for day 1-7; (3) commercial medium + 5% Fetal Calf Serum (FCS) for day 1-7; and (4) commercial medium for the first 2 days and supplemented with 5% FCS from day 3 to 7 (Sequential commercial medium). Embryos cultured in m-SOF is significantly lower (P<0.05) than other treatments in terms of cleavage in blastocyst cell count (P<0.05). On the other hand, sequential media has improved (P<0.05) in terms of morula, blastocyst development and blastocysts cell count. Since the sequential commercial media is the most efficient treatment it was chosen for embryo grading using International Embryo Transfer Society (IETS) standard, vitrification and warming using Cryotech method. The expanded balstocyst with the IETS code of of 1 when vitrified had the highest rates of re-expansion (92.50%) and hatching development (82.50%) at the post-thaw analysis.
In conclusion, adding Fetal Calf Serum on the commercial medium after 3 days of culture produced high rate of embryo development and better quality blastocysts. The success of vitrification is essentially dependent on the culture system, the developmental stage of the embryo, the quality of the embryo, the cell count and lastly the vitrification technique.