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The aim of the study was to compare the effect of different synchronization protocols on oocyte retrieval and blastocyst production in vitro. Twelve Simmental heifers were randomly allocated to one of three synchronization groups. In the 1st group heifers were synchronized with two PGF2α injections in 11-days interval. In the 2nd group heifers were synchronized the same way and dominant follicles (DF) were removed 36 hours before pFSH stimulation. In the 3rd group a progestin ear implant was inserted for 10 days and DF were aspirated 36 hours before pFSH stimulation. The same stimulation protocol with pFSH, starting on Day 9/10 of cycle, was used in all treatment groups. Ovum pick-up (OPU) was performed 48 hours after the last pFSH injection. The number of aspirated follicles, number and quality of retrieved oocytes were recorded. Oocytes were matured, fertilized and cultured in vitro in SOFaaBSA until Day 9. The mean DF diameter and the mean number of expanded oocytes showed a tendency towards signififi cance (0.05 ≤ P ≤ 0.10) in the progestin treatment group. No signififi cant differences between treatment groups were observed in terms of cleavage rate on Day 2, morula/blastocyst rate on Day 7 and hatched blastocysts rate on Day 9. The results indicated that progestin treatment did not prevent the establishment of follicular dominance on the ovaries of heifers. Furthermore, the synchronization protocol did not affect the number of follicles and the recovered oocytes, or the number of in vitro produced embryos.

The aim of this research was to compare the developmental competence of oocytes recovered from slaughterhouse ovaries (SO) and those recovered in vivo by ovum pick up (OPU). OPU was performed in 6 donor heifers synchronized with PGF2 and stimulated with pFSH, twice a day during two days. OPU was repeated once a week for six consecutive weeks. The control group consisted of slaughterhouse-derived oocytes. The number of aspirated follicles, retrieved oocytes and oocyte recovery rate were recorded. Oocytes of grade 1 and 2 were matured, fertilized and cultured in vitro in SOFaaBSA until Day 9. The cleavage rates on Day 2, the total number of morulas and blastocysts on Day 7 and the numbers of hatched blastocysts on Day 9 were recorded. Differential staining of the inner cell mass (ICM) and trophectoderm cells (TE) were performed on randome sample of Day 7 blastocysts (n=24). Significantly more follicles were aspirated from SO (19.3 versus 11.5, P

The success of ovum pick-up (OPU) and in vitro embryo production considerably depends on the number and the quality of retrieved oocytes per session and also on the culture conditions. The aim of the study was to compare the effect of different synchronization protocols on oocyte retrieval and blastocyst production in vitro in FSH stimulated Simmental heifers. Twenty-eight normal cyclic Simmental heifers, aged between 14 and 20 months were selected based on transrectal palpation for oocyte donors. They were randomly allocated to one of three synchronization groups. In the 1st (PGFx2) group heifers (n=10) were synchronized with two prostaglandin F2 injections at 11-day interval. In the 2nd (PGF + DFR) group heifers (n=8) were synchronized with two prostaglandin F2 treatments at 11-day interval and dominant follicles (>8 mm) were aspirated (DFR: dominant follicle removal) 36 hours before FSH stimulation. In the 3rd (Crestar + DFR) group (n=10) a norgestomet ear implant without the prescribed oestrogen injection (Crestar® ; , Intervet, Begium) was inserted for 10 days. The implants were removed and dominant follicles were aspirated 36 hours before FSH stimulation. The stimulation with pFSH (Folltropin® ; -V, Vetrepharm Inc., London, Canada) was the same fir all three groups and it was administered twice a day, during two days beginning on the day 9 or 10 of the estrous cycle. The total amount of pFSH administered was 200 mg NIH-FSH-P1 in 4 equivalent doses. OPU was performed 48 hours after the last FSH injection. Only good quality oocytes were matured, fertilized and cultured in vitro in SOFaaBSA till the Day 9. Cultured embryos were evaluated morphologically according to IETS standards. The cleavage rates on Day 2, the total number of morulas (M) and blastocysts (Bl) on Day 7 and the number of hatched blastocysts (hBl) on Day 9 were recorded. The results were statistically analyzed with ANOVA (StatSoft, Statistic, version 7.1.) and with Tukey, s tests post-hoc analysis.The results are presented in the table. Table: Effect of different synchronization protocols on oocyte retrieval and IVF/IVC results in FSH stimulated Simmental heifers (mean± ; SD) Synchronization protocol Follicles aspirated Oocytes retrieved Oocytes in IVP Cleavage (%) M/Bl (%) hBL (%) PGFx2 group (n=10) 14.5 (± ; 3.9)a 10.3 (± ; 5.2)b 9.5 (± ; 5.6)a 86.8 (± ; 1.8)a 41.1 (± ; 2, 2) a 22.4 (± ; 1.8) a PGF + DFR group (n=8) 13.3 (± ; 3.9) a 7.6 (± ; 4.0) a 6.9 (± ; 4.5) ab 91.0 (± ; 1.3) a 28.9 (± ; 2.2) b 12.4 (± ; 1.4) b Crestar + DFR group (n=10) 13.1 (± ; 4.1) a 9.1 (± ; 4.1) ab 5.9 (± ; 3.6) b 94.7 (± ; 0.8) a 43.6 (± ; 2.0)a 23.2 (± ; 1.5) a Values with different superscripts within the same columns differ significantly (P