9 Ovum pick-up/in vitro embryo production (OPU-IVP), an alternative means for infertile or bad donor cows to produce embryos

For a farmer, it is a great challenge to obtain many progeny from their cows with a high genetic value. To deal with reproductive incapacity of some female by classical reproduction technologies (AI or multiple ovulation and embryo transfer), ovum pick-up for in vitro production of embryos (OPU-IVP) could be an alternative technology to resolve reproductive problems. The aim of this field study was to investigate the IVP of open donors considered “infertile” and to compare it with that of “fertile” donors, in a retrospective analysis of files compiled by AURIVA Biotechnologies (Denguin, France), including 559 OPU from 121 donors over a 9-year period from 2012 to 2020 (Table 1). To consider the donor effect, only donors submitted to at least two OPU-IVP sessions were included in the statistical analysis. Donors were stimulated with decreasing doses of porcine (p)FSH (Stimufol; Reprobiol) twice daily over 3 days (total dose: 300 µg for cows and 200 µg for heifers). Cumulus–oocyte complexes (COCs) were collected by OPU 12 to 24 h after the last FSH injection and in vitro matured (IVM) using a standard protocol. COCs were fertilised with frozen-thawed unsorted or X-sorted sperm in mod-TALP medium using different non-pretested bulls. Presumptive zygotes were cultured in yssynthetic oviductal fluid (SOF) medium up to Day 7 at 38.5°C under 5% CO₂ and 5% O₂ with maximum humidity. Grade 1 expanded blastocysts (G1EB; IETS classification) were recorded on Days 6.5 and 7. For a subgroup of infertile dairy cows (326 OPU), we demonstrated that the use of sexed semen did not modify the G1EB/IVM COCs ratio (59% vs 57% for unsexed semen). The influence of different factors (breed type, parity, fertile or infertile group) on embryo production was analysed using a general linear model, taking into account the multiple interactions between factors. Beef donors tended to produce much more viable COCs that successfully developed into G1EB. The “infertile” group produced fewer COCs selected for IVM compared with the fertile group, but the competence of COCs for IVP was similar regardless of reproductive status. In dairy cattle, the number of G1EB produced in infertile cows was close to that in the fertile group. Despite the limited number of animals, our retrospective study showed that OPU-IVP is a way to obtain offspring from females with reproductive incapacity by classical reproduction technologies. Our data are in general agreement with most prospective studies reporting enhanced IVP in beef cattle compared with dairy cattle.

Table 1.  Mean (SD) of IVM COCs, G1EB per OPU, and G1EB/IVM COC ratio