engleski

Effect of repeated FSH stimulation prior to ovum pick-up on developmental competence of bovine oocytes in simmental heifers

Ultrasound transvaginal ovum pick-up was performed in 6 Simmental heifers aged 14 to 18 months. Heifers were synchronized with PGF2 and stimulated with pFSH twice a day during two days (Folltropin® ; ; ; ; -V, Vetrepharm Inc., London, Canada, a total dose: 200 mg NIH-FSH-P1). OPU was performed 48 hours after the last FSH injection and the procedure was repeated four times at 2-week intervals (OPU-A). After a six-week rest period, ovarian stimulations with pFSH and oocyte recoveries were carried out again (OPU-B). Retrieved oocytes were classified in three quality categories: G1 (oocytes with a homogenous ooplasm and a complete or incomplete cumulus cells), G2 (oocytes with a dark or unevenly granulated ooplasm) and G3 oocytes with degenerated ooplasm. The mean number of oocytes in category G1 was 5.7  0.9 for OPU-A and 4.6  0.7 for OPU-B group. The mean number of oocytes in the G2 and G3 categories for OPU-A and OPU-B groups were: 1.4  0.4, 0.2  0.1 and 0.9  0.2, 0.4  0.2, respectively. Only G1 classified oocytes were matured, fertilized and cultured in vitro in SOFaaBSA medium till the Day 10. Cultured embryos were evaluated morphologically according to IETS standards. The percentage of oocytes reaching the morula/blastocyst stage on Day 7 and of hatched blastocysts on Day 10 was 43.1% and 35.1% and 33.1% and 34.8% for OPU-A and OPU-B, respectively. The results show that the repeated FSH stimulation prior to ovum pick-up does not affect the developmental competence of bovine oocytes in Simmental heifers..

Simmental heifer; superovulation; ovum pick-up; bovine oocyte; developmental competence

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