123 Efficiency of embryo production using ovum pickup oocytes recovered from stimulated and nonstimulated cows
R. Y. Chinarov A , G. N. Singina A , V. Havlicek B , N. P. Taradajnic A , T. E. Taradajnic A and S. V. Pozyabin CA L. K. Ernst Federal Science Center for Animal Husbandry, Podolsk, Russia;
B Department of Animal Breeding and Genetics, University of Veterinary Medicine, Vienna, Austria;
C Moscow Academy of Veterinary Medicine and Biotechnology named after K. I. Skryabin, Moscow, Russia
Reproduction, Fertility and Development 33(2) 169-170 https://doi.org/10.1071/RDv33n2Ab123
Published: 8 January 2021
Abstract
Recovery of oocytes from live animals through ultrasound-guided transvaginal follicular aspiration (ovum pickup, OPU) is an essential element of modern livestock development. To increase the number of OPU oocytes retrieved, hormonal stimulation is broadly applied; however, the results are ambiguous. The aim of the present study was to compare recovery rate, quality of oocytes, and efficiency of in vitro production of cattle embryos using OPU oocytes derived from hormonal treated and untreated cows. The study was performed in Simmental heifers at the age of 17 to 23 months. The heifers in the first group (n = 7) were previously synchronized using prostaglandin F2α (Estrumate, MSD Animal Health) and gonadotrophin-releasing hormone (GnRH; Receptal, MSD Animal Health) and then underwent superstimulation with Stimofol (Reprobiol SPRL, Belgium) in a total amount of 0.25 mg of FSH and 0.05 mg of LH in a treatment of 6 injections on 3 consecutive days starting on Day −4 before OPU. The heifers of the second group (n = 2) underwent OPU once a week for 5 weeks (10 OPU sessions). Groups of recovered cumulus–oocyte complexes (COCs) were matured in TCM-199 containing 10% fetal calf serum, 1 mM Na-pyruvate, 50 μg mL−1 gentamycin, 10 μg mL−1 FSH, and 10 μg mL−1 LH for 24 h, fertilized in Fert-TALP (Tyrode’s-albumin-lactate-pyruvate) for 18 to 20 h, and cultured in CR1aa medium for 7 days. All steps of IVP were performed at 38.5°C with 5% CO2 and 90% humidity. The cleavage and blastocysts rates were assessed on Day 2 and 7, respectively. In addition, Day-7 blastocysts were fixed, and the total cell number was determined using 4′,6-diamidino-2-phenylindole (DAPI) staining. The data were analysed by ANOVA using SigmaStat software package. As expected, the number of aspirated follicles per session in the first group of cows was higher than that in the second group: 14.6 ± 1.2 vs. 6.8 ± 0.5 (P < 0.05). In total, 54 and 42 COCs were collected, which corresponds to recovery rates of 54.5 ± 7.7 and 61.3 ± 4.9% for stimulated and nonstimulated cows, respectively. After the quality evaluation, 36 COCs of SS heifers (67.2 ± 1.9%) and 31 COCs of non-SS heifers (75.3 ± 5.0%) were selected for IVP. We did not observe a significant difference in cleavage rate between two groups: 77.8% in the SS group vs. 71.0% in the non-SS group, whereas the rate of blastocyst production was higher (P < 0.05) for SS heifers (25.0%) compared with non-SS animals (16.1%). The total number of cells in Day 7 blastocysts was significantly (P < 0.01) higher in the first group (89.8 ± 1.3) compared with the second group (70.6 ± 3.2). Thus, superstimulation of heifers before OPU increases the efficiency of oocyte retrieval by ultrasound-guided transvaginal follicular aspiration as well as the developmental competence of OPU-derived bovine oocytes in vitro.
These studies were performed under financial support of the Russian Science Foundation (project No. 19-16-00115) and the Ministry of Science and Higher Education of Russia.
