The Construction of Cloned Sika Deer Embryos ( Cervus nippon hortulorum ) by Demecolcine Auxiliary Enucleation

Oocyte holding in the Iberian red deer (Cervus elaphus hispanicus): Effect of initial oocyte quality and epidermal growth factor addition on in vitro maturation

Current in vitro embryo production protocols in the Iberian red deer (Cervus elaphus hispanicus) need to be optimized; oocyte harvesting in situ followed by overnight holding could reduce the human effort and shipping costs. In our work, post-mortem ovaries were retrieved, and the oocytes were harvested and allocated to G1 group (good quality) or G2 + G3 group (low quality). The oocytes were separately subjected to immediate in vitro maturation (IVM) or held overnight in a holding medium composed of 40% of TCM 199 with Earle's salts, 40% TCM 199 with Hanks' salts and 20% fetal bovine serum (FBS), at room temperature (16 hr). In vitro maturation was carried out in a basal medium supplemented or not with 50 ng/ml of epidermal growth factor (EGF). Our data showed that addition of EGF to the maturation medium increases the percentage of G1 oocytes reaching metaphase II (3.9% vs. 50%, basal vs. EGF; p < .001) and decreased their degeneration rate (69.9% vs. 22.2%, basal vs. EGF; p < .01) when oocytes were immediately matured. Overnight holding increased the meiotic competence of G1 oocytes (37.5% matured in basal medium) and EGF increased prophase arrest in G2 + G3 oocytes (16.1% vs. 38.8% in germinal vesicle [GV] stage in basal medium vs. EGF added medium; p < .05). Our data demonstrate that oocyte holding can be used in Iberian red deer oocytes. Interestingly, EGF addition increases the oocytes' meiotic competence in immediately matured oocytes but not after oocyte holding depending upon initial oocyte quality.

The impact of ovarian stimulation protocol on oocyte quality, subsequent in vitro embryo development, and pregnancy after transfer to recipients in Eld's deer (Rucervus eldii thamin)

Propagating genetically valuable individuals through oocyte collection, in vitro fertilization (IVF) and embryo transfer is critical to maintain sustainable populations of the endangered Eld's deer. The objectives of this study were to assess the impact of exogenous FSH injections on (1) the number and in vitro competence of oocytes collected and (2) the developmental potential of resulting IVF embryos after transfer into recipients during the breeding season (February-April). In a pilot experiment, estrus synchronization was conducted in three surplus females (using intravaginal progesterone-releasing devices, CIDRG for 14 days and injections of buserelin (a GnRH agonist). Five days after CIDR removal, ovaries were excised, minced and a total of 133 oocytes were recovered. Following in vitro maturation (IVM) and IVF, 63% of the oocytes formed embryos but only 5% reached the blastocyst stage. In a subsequent study, follicle numbers and diameters were compared between synchronized does stimulated with 0 or 80 mg FSH (-FSH and +FSH; n = 8 does in each group) and oocytes collected either by laparoscopic ovum pick-up or ovariectomy. FSH stimulation increased the main follicular diameter from 2-3 mm to 4-5 mm (P < 0.05) but not the oocyte number (∼20/donor) or the percentage of good quality oocytes (57%) regardless of the treatment. FSH stimulation did not either affect the percentage of cleaved embryos after IVF (25-35%; P > 0.05). Lastly, embryos at the 2-to 8-cell stage (from either + FSH or -FSH groups) were transferred into the oviducts of 11 synchronized recipients. With the +FSH embryos, three pregnancies failed between 90 and 120 days of gestation and two fawns that were born preterm (Days 215 and 224 of gestation) died at birth. In the -FSH group one healthy female fawn was born on Day 234 of gestation. This is the first report of a successful in vitro embryo production and subsequent birth of a live Eld's deer fawn. Further investigations are required to improve IVM/IVF success and the developmental potential of the embryos.