122 Colour-Doppler ultrasonography as a tool for oocyte donor selection
Authors: Villaseñor-González F. , Álvarez-Gallardo H. , Kjelland M. , Velázquez-Roque A. , Romo S. 
Published: January 2021

Colour-Doppler ultrasonography (CDU) has been applied for a more detailed examination of the ovary and uterus, mainly local blood flow in ovarian follicles and the corpus luteum (CL). The main use of CDU is for the diagnosis of early pregnancy or the selection of recipients for embryo transfer in cattle; however, this tool can also be used to select oocyte donors according to blood flow to the ovary. The concept is that more blood flow in the ovary is conducive to a healthier intraovarian environment (e.g. higher progesterone levels and removal of reactive oxygen species), yielding higher quality oocytes. The objective of this research was to evaluate invitro embryo production (IVP) after selection of oocyte donors, considering ovary irrigation before ovum pickup (OPU). The research was carried out in the reproduction laboratory at the Palominos Ranch (Jalisco, México). The oocyte donors (n=15) were synchronized before each round of OPU using an intravaginal device (1.9g of progesterone) with oestradiol benzoate (2mg) and cloprostenol sodium (500µg) on Day 0, to avoid the presence of a corpus luteum and to synchronize the follicular wave. On Day 6, the intravaginal device was removed and OPU was performed. All Angus breed donors between 3 and 5 years old with a body condition score between 5–6 (scale 1–9, where 1 is extremely thin and 9 is very obese) and were evaluated with transrectal CDU (Sonoscape S2™) with a linear-array probe (7.5MHz) before the first OPU session only. The oocyte donors were classified subjectively into three categories: low blood flow (LBF, ∼30% ovarian area), median blood flow (MBF, ∼50% ovarian area), and high blood flow (HBF, ∼70% ovarian area) and were submitted to 3 cycles of IVP each (45 total cycles). Semen from a proven bull for IVF was used during all IVP cycles. All oocytes collected from each donor were used in IVF with the same semen in all IVP cycles. The total oocytes collected, and percentages of viable oocytes, cleavage, and blastocysts on Day 7 of culture were evaluated. Statistical analysis was carried out using the GLM procedure of SAS software (version 9.3; SAS Institute Inc.) to evaluate the results of LBF, MBF, and HBF (P-value=0.05). Total oocyte recovery was 11.28±1.92, 10.06±1.31, and 15.52±1.05 for HBF, MBF, and LBF, respectively, being significantly higher for LBF (P&lt;0.05). There were no differences in viable oocytes among groups. Cleavage rates were 53.04%±3.43 for HBF, 43.18%±2.34 for MBF, and 43.69%±1.89 for LBF, being significantly higher for HBF (P&lt;0.05). Percentage of blastocysts on Day 7 was 38.16%±3.80 for HBF, 30.11%±2.60 for MBF, and 17.78%±2.10 for LBF. This value tended to be significantly higher for HBF than MBF, and both were significantly superior to LBF (P&lt;0.05). In conclusion, under the conditions of this research, although LBF donors had more total recovered oocytes, blastocyst rates were increased in HBF and MBF donors. Therefore, based on the results of the present study, CDU can be a useful tool for the selection of oocyte donors.