Hormonal treatments for increasing the oocyte and embryo production in an OPU–IVP system

The objective was to enhance the inherent developmental ability of bovine oocytes retrieved by ultrasound-guided transvaginal aspiration. Various hormonal regimes were utilized to produce partially matured oocytes in vivo, in order to improve embryo development following IVF. In the first experiment, a two-by-two factorial design was used with FSH (multiple versus single dose) and im administration of LH (yes versus no) 6 h prior to OPU. In all protocols (which lasted for nine consecutive weeks), ovarian stimulation was performed in the presence of a CIDR. One FSH administration was adequate for ovarian stimulation (9.33 ± 0.7 and 10.14 ± 0.7 follicles per cow per OPU session); however, multiple injections increased (P < 0.05) follicular response (12.97 ± 0.7 and 13.97 ± 0.7). In the second experiment, a two-by-two factorial design was used to compare the effects, during ovarian stimulation, of the presence or absence of CIDR, and iv treatment with LH 6 h prior to OPU (yes versus no), on oocyte competence (judged by blastocyst development rates following IVF). Presence of CIDR during superstimulation had no effect on the follicular response. Administration of LH 6 h prior to OPU increased (P < 0.05) the oocytes of higher morphological grades, and in the absence of a CIDR, improved (P < 0.05) blastocyst development rate. Treatment with LH, 6 h prior to OPU without the use of CIDR during ovarian stimulation, resulted in 2.89 ± 0.4 blastocysts per cow per OPU session as compared to 1.56 ± 0.4, 1.56 ± 0.4 and 1.33 ± 0.4 for all other groups. In conclusion, compared to single administration, multiple FSH administration increased (P < 0.05) available follicles for aspiration. Moreover, when ovarian stimulation in the absence of CIDR was followed by administration of LH 6 h prior to OPU, it increased (P < 0.05) the number of blastocysts per OPU session.