Efficiency of Ovsynch for Synchronization of Oocyte Donor Cows for Embryo Production In Vitro

Svrha ovog rada bila je istražiti uspjeh sinkronizacije krava davateljica jajnih stanica OvSynch protokolom. Istraživan je utjecaj OvSynch-a na kvalitetu žutog tijela i prisustvo dominantnog folikula prije započinjanja superovulacijskog tretmana, na dinamiku rasta folikula i uspjeh aspiracije jajnih stanica za oplodnju in vitro. Šest krava holštajn frizijske pasmine u dobi od 3-6 godina sinkronizirane su sintetskim analogom GnRH (0. i 9. dan) i sintetskim analogom prostaglandina (7. dan). Superovulacijski postupak započet je u lutealnoj fazi ciklusa s pomoću visokopurificiraniog FSH preparata apliciranog dva puta dnevno tijekom dva dana u padajućim dozama. Neposredno prije započinjanja superovulacijskog tretmana ultrazvučno je zabilježeno prisustvo dominantnog folikula i žutog tijela kod krava davateljica te kvaliteta žutog tijela mjerenjem razine progesterona. Dinamika rasta folikula praćena je rektalnim i ultrazvučnim pregledima 24 i 36 sati nakon zadnje aplikacije FSH. Transvaginalna aspiracija jajnih stanica učinjena je 36 sati nakon zadnje injekcije FSH. Folikuli su podijeljeni prema promjeru u sljedeće razrede: folikuli 15 mm. Bilježen je broj aspiriranih folikula prema veličini, broj aspiriranih jajnih stanica i uspjeh aspiracije. Aspirirane jajne stanice morfološki su ocjenjene te prema izgledu stanica kumulusa i ooplazme svrstane u pet kategorija kvalitete (G1, G2, G3 i G4 i ekspandirane jajne stanice). Prisustvo dominantnog folikula na jajnicima, koji je utvrđen u 4 davateljice prije započinjanja superovulacijskog postupka, utjecao je na dinamiku rasta folikula po kategorijama. Kod davateljica koje su imale prisutan DF bilo je značajno više folikula 15 mm (p 10 ng/mL, dok je kod davateljica koje su imale koncentraciju progesterona > 10 ng/mL prosječan broj folikula >15 mm bio je značajno viši (p<0,05). Prosječan broj aspiriranih jajnih stanica iznosio je 7,16 ± 1,09, a kvalitetnih jajnih stanica (G1, G2 i G3) prikladnih za IVF iznosio je 4,50 ± 0,31. Uspjeh aspiracije (RR%) iznosio je 60,00 ± 2,97%. Rezultati istraživanja pokazuju da je OvSynch protokol uspješno sinkronizirao estrus u krava davateljica jajnih stanica za OPU/IVP i pozitivno utjecao na folikularni razvoj, a time i na uspjeh aspiracije jajnih stanica za oplodnju in vitro.The aim of this study was to evaluate the efficacy of OvSynch protocol for synchronization of oocyte donor cows. The effect of OvSynch on quality of corpora lutea and the presence of dominant follicle prior to superovulation, the dynamics of follicular growth and oocyte recovery rate after ovum pick-up was investigated. Six Holstein-Friesian cows, three to six years of age, were synchronized with a synthetic GnRH analogue (day 0 and 9) and with a synthetic prostaglandin analogue (day 7). Superovulation started in a luteal phase with a highly purified FSH applied twice a day for two days in decreasing doses. Just before the beginning of superovulation, the presence of a dominant follicle and corpora lutea in donor cows was recorded using ultrasound imaging. The quality of corpora lutea was recorded by measuring blood progesterone levels. Rectal examinations and ultrasound imaging, 24 and 36 hours after last application of FSH, were used to track the follicular dynamics. Transvaginal ovum pick-up was performed 36 hours after the last FSH injection. Follicles were ranked by diameter into following categories: follicles 15 mm. The number of aspirated follicles according to size, the number of retrieved oocytes and the oocyte recovery rate were recorded. Collected oocytes were classified, based on compactness of cumulus cells and morphology of ooplasm, into five quality categories (G1, G2, G3, G4, and expanded cumulus oocytes). Presence of a dominant follicle in the ovaries, which has been recorded in 4 donor cows prior to superovulatory treatment, affected the follicular dynamics of ovarian follicular growth of all categories. Donor cows with the presence of DF had significantly more follicles 15 mm (p10 ng/mL, while a group of donor cows with progesterone levels >10 ng/mL had significantly higher (p15 mm. The average number of oocytes recovered was 7,16 ± 1,09. The number of high quality oocytes (G1, G2 and G3) appropriate for IVF was 4,50 ± 0,31. The recovery rate (RR%) after OPU was 60,00 ± 2,97%. These results demonstrate that the OvSynch protocol effectively synchronized oestrus of oocyte donor cows and had a positive effect on a follicular growth and oocyte recovery rate after transvaginal aspiration of oocytes for in vitro fertilization