In vitro production of sheep embryos using laparoscopic folliculocentesis: Alternative gonadotrophin treatments for stimulation of oocyte donors

Three different gonadotrophin regimens for the stimulation of donors for laparoscopic folliculocentesis were tested in a total of 142 ewes. The recovered oocytes were subjected to in vitro maturation, fertilization, and culture (IVM/IVF/IVC) for 7 d using standard procedures for sheep. The estrous cycles of all ewes were synchronized using intravaginal sponges containing 60 mg of medroxyprogesterone acetate (MPA) inserted for 14 d. In Experiment 1, all ewes were superovulated with a total dose of 125 IU FSH and 125 IU LH. One-half of the ewes received the gonadotrophin treatment in 4 decreasing doses at 12-h intervals starting 48 h before follicle aspiration (Control), while the other half received the total dose in a single injection at -24 h before collection (Oneshot). There were no significant differences between treatments for recovery rate (81.6 +/- 5.3 vs 77.4 +/- 10.3), cleavage rate (60.6 +/- 20.8 vs 61.4 +/- 23.4), or normal development to the blastocyst stage (20.8 +/- 18.2 vs 13.1 +/- 10.3). However, a higher percentage of ewes produced at least 1 normal blastocyst in the Control group (56.4 vs 31.6%; P0.05). In Experiment 2, the control regimen was repeated in half of the ewes, while the remainder were treated with half of the FSH total dose plus 500 IU eCG in a single injection at -24 h before oocyte collection (Oneshot-eCG). The recovery rate (80.9 +/- 5.6 vs 73.3 +/- 15.3), cleavage rate (76.8 +/-19.9 vs 79.7 +/- 22.6), normal development to blastocysts (19.2 +/- 15.3 vs 23.3 +/- 10.7), and percentage of ewes producing at least 1 normal blastocyst (55.9 vs 51.6%) did not differ between treatments. The large variability observed between ewes in the production of normal blastocysts is comparable to that observed with standard MOET procedures, in which a proportion of donors fail to produce good embryos. With the in vitro procedures described here, we were able to produce normal embryos from more than half of the treated ewes, indicating that the technology is useful for the multiplication of genetically valuable animals affected by temporary or irreversible infertility.