Effects of Superovulation with oFSH and Norgestomet/GnRH‐Controlled Release of the LH Surge on Hormone Concentrations, and Yield of Oocytes and Embryos at Specific Developmental Stages

Abstract

The objective of this study was to evaluate a new superovulation procedure with oFSH after temporary suppression of the endogenous LH surge by norgestomet followed by administration of GnRH, to collect bovine oocytes and embryos at specific developmental stages. Since 1999, our research group applies this superovulation procedure with controlled release of the endogenous LH surge. The objective of this study is to verify if this procedure is reliable for collection of oocytes and embryos at specific time points of development and if it produces a sufficient number of both oocytes and embryos of good quality. This procedure was validated regarding to hormonal characteristics, superovulatory response and both oocyte and embryo yield at different times of in vivo development. The results demonstrate that the procedure used to control the occurrence of the pre-ovulatory LH surge was effective in 92% of the animals (n = 238) and even in 99% of the animals the oocytes and embryos were collected at the intended stage of development. The superovulatory response and both oocyte, embryo yield and quality were similar to the average yield in Europe reported by Association Européenne de transfert embryonnaire (AETE). In conclusion, this superovulation procedure provides a valid tool to collect oocytes and embryos at specific time points of development.

Transcriptional effect of the LH surge in bovine granulosa cells during the peri-ovulation period

“…In mono-ovulatory species such as humans and cows, ovarian stimulation with gonadotropins is widely used to stimulate the growing cohort of follicles to reach the ovulatory phase and produce an increased number of fertilizable oocytes as opposed to only one. The multiple FSH injections followed by a coasting period and an LH injection have been reported to generate developmentally competent oocytes and good to high embryonic developmental rates (Blondin et al 2002, Chaubal et al 2007, Knijn et al 2011. Although some differences in gene expression compared with natural cycles are expected, it has been demonstrated that stimulation with FSH, compared with those performed with eCG, has a profile of 17b-estradiol similar to those observed in a natural cycle (Soumano et al 1996, Knijn et al 2011).…”

“…The multiple FSH injections followed by a coasting period and an LH injection have been reported to generate developmentally competent oocytes and good to high embryonic developmental rates (Blondin et al 2002, Chaubal et al 2007, Knijn et al 2011. Although some differences in gene expression compared with natural cycles are expected, it has been demonstrated that stimulation with FSH, compared with those performed with eCG, has a profile of 17b-estradiol similar to those observed in a natural cycle (Soumano et al 1996, Knijn et al 2011). However, little was previously known about the gene expression cascade that follows the LH surge and the molecular determinants involved in ovulation and the last stage of GC differentiation.…”

“…To obtain the different GC groups at specific time points, ovarian stimulation treatments were administered to cows. The ovarian stimulation protocol using FSH with controlled release of the LH surge has been examined by one other group since 1999 (Knijn et al 2011). This method was proven to be efficient for the collection of GCs and oocytes/embryos at specific time points, since the accuracy in determining the time of the LH surge was effective in 92% of cases (nZ238; Knijn et al 2011).…”

“…The ovarian stimulation protocol using FSH with controlled release of the LH surge has been examined by one other group since 1999 (Knijn et al 2011). This method was proven to be efficient for the collection of GCs and oocytes/embryos at specific time points, since the accuracy in determining the time of the LH surge was effective in 92% of cases (nZ238; Knijn et al 2011). In mono-ovulatory species such as humans and cows, ovarian stimulation with gonadotropins is widely used to stimulate the growing cohort of follicles to reach the ovulatory phase and produce an increased number of fertilizable oocytes as opposed to only one.…”

“…The ovarian stimulation treatment and ovariectomy protocol were described in detail by Knijn et al (2002Knijn et al ( , 2011. Briefly, normally cyclic Holstein Friesan cows (nZ30) were presynchronized using an ear implant for 9 days (3 mg norgestomet, Crestar; Intervet International BV, Boxmeer, The Netherlands) and a single administration of 3 mg norgestomet and 5 mg estradiol valerate (Intervet International BV).…”