Developmental competence of bovine oocytes frozen at different cooling rates.
Experiments were conducted to determine the optimal cooling conditions for improving the developmental competence of in vitro-matured bovine oocytes when frozen in 1.6 M 1,2-propanediol. Bovine oocytes were cooled from 0 degree to -5.5 degrees C at 1 degree C/min, seeded, and then cooled to -30 degrees C at different cooling rates (0.3 degree, 0.6 degree or 0.9 degree C/min) and then plunged into LN2. When frozen-thawed oocytes were fertilized in vitro, the proportions of fertilization and developmental competence did not differ among the three groups frozen at different cooling rates. The findings indicated that a cooling rate of less than 1.0 degree C/min in the freezing procedure did not affect the developmental competence of postthaw in vitro-matured bovine oocytes.
Otoi
T
T
Tokushima Prefectural Beef Cattle and Swine Experiment Station, Japan.
Tachikawa
S
S
Kondo
S
S
Takagi
M
M
Suzuki
T
T
D000818:Animals; D002417:Cattle; D015925:Cryopreservation / Q000379:methods*; D003451:Cryoprotective Agents; D005069:Evaluation Studies as Topic; D005260:Female; D005307:Fertilization in Vitro; D066298:In Vitro Techniques; D009865:Oocytes / Q000254:growth & development; D019946:Propylene Glycol; D011409:Propylene Glycols; D013997:Time Factors
D003451:Cryoprotective Agents; D011409:Propylene Glycols; D019946:Propylene Glycol