In vitro embryo production is a cutting-edge technology in constant evolution and has been used routinely. With the objective of improving genetic value, recent studies have been focused on the production of high-performance descendants from early prepubertal animals. The aim of this study was to compare hormonal protocols of ovarian stimulation for laparoscopic ovum pick-up in prepubertal sheep, to determine ovarian response and number of oocytes. For this study, 36 Santa Ines sheep, aged between 4 and 8 weeks, were submitted to a progestogen-based, short-term ovulation induction protocol (without use of prostaglandin F2α), and following 36 h, ovarian stimulation (300 IU of eCG) associated with different regimens of administration of FSH, according to experimental group. The ewes were divided into 1 of 6 groups: 2 groups received 80 mg of FSH by either single administration in the first group (G80U) or multiple constant administrations at 12-h intervals in the second group (G80M); animals belonging to 2 other groups received 160 mg in the same fashion, in a single-dose regimen (group G160U) or in multiple administrations (group G160M). The other 2 groups constituted the control groups: one received no hormonal treatment for ovulation induction and ovarian stimulation (GCN); the other received the ovulation induction protocol, but no ovulation stimulation was carried out (GCI). The animals were submitted to laparoscopic ovum pick-up 48 h following the beginning of the ovarian stimulation. The number of follicles viewed (FV), aspirated (FA), and recovered (OR) laparoscopically was recorded. Data were assessed using the one-way ANOVA test, and the comparison among groups was carried out using the Tukey test. The mean of follicles visualised, aspirated, and oocytes recovered are shown in Table 1. Group G160U had a better result regarding OR compared with the other groups. Moreover, the current study highlights that laparoscopic ovum pick-up for in vitro maturation using prepubertal ewes is viable for commercial purposes. More studies are required in order to improve the quality of oocytes and successful in vitro maturation rates.
Table 1.Results of visualised follicles (VF), aspirated follicles (AF), and oocytes retrieved (OR)
Predictors of ovarian response: progress towards individualized treatment in ovulation induction and ovarian stimulation
