249 OPTIMIZING DONOR EFFICIENCY WITH FOLLICLE STIMULATING HORMONE SUPERSTIMULATION IN A COMMERCIAL IN VITRO FERTILIZATION PROGRAM IN HOLSTEINS

Commercial IVF programs in Holstein (HO) donors in North America require that not only quantity, but also quality of embryos be increased. These programs are intended to produce the maximal number of offspring from elite females and males over a short period of time. Optimal embryo quality is needed for cryopreservation (for embryo trade and a recurrent problem with a shortage of recipients) and to maximize the number of pregnancies. Preliminary studies in our laboratory showed a significant increase in blastocyst rates following superstimulation with FSH (42 v. 22%; P < 0.0001). The objective of this presentation is to describe parameters of practical importance that affect donor efficiency in an IVF program that involves superstimulation. Data from commercial IVF records were retrospectively analysed. All in-house HO donors admitted since 2013 and at least 12 months of age at the time of collection were included. In total, 1387 ultrasound-guided follicle aspirations (ovum pickup) were performed on 376 HO donors following a constant dose, 6 injections, pFSH (Folltropin-V, Vetoquinol) protocol with a 30- to 43-h coasting period. The IVF system included maturation of cumulus-oocyte complex in TCM-199 based medium, fertilization with frozen‐thawed unsexed, sexed, and reverse-sorted semen, as well as culture in modified synthetic oviduct fluid under mineral oil in a humidified atmosphere containing 6.9% CO2, 5% O2, and 88.1% N2 at 38.5°C for 7 days. Antral follicular counts (AFC), assessed with a 7.5-MHz endovaginal ultrasound probe at random stages during diestrus, were correlated with the number of follicles stimulated. Average number of follicles stimulated was 13.9 (median = 12, maximum = 111) with 74.6% of follicles between 7 and 15 mm at the time of ovum pickup. Average recovery rate was 73.2% and tended to decrease as size of the follicles increased. Transferable embryos rate (TER), defined as the number of IETS quality 1 and 2 embryos produced out of the number of oocytes placed in maturation per ovum pickup session, was 42.1% (median = 43.7%, maximum = 100%). Nearly two-thirds of the transferable embryos produced met our freezability criteria. When these frozen embryos were transferred, over 60% of the recipients were pregnant at 30 days. No difference was observed in efficiency of pregnant versus open donors for TER. In most donors, OPU were repeated every 2 weeks, regardless of pregnancy status. The effect of multiple stimulations on the ability of a donor to maintain its efficiency was assessed by comparing number of follicles stimulated and TER in the first and last 3 collections in donors that had at least 10 collections, with no significant difference. Individual variation appeared very high, as approximately one-third of the donors produced two-thirds of the embryos. When defining a poor responder based on the number of follicles available for ovum pickup following superstimulation, TER was lower in donors with <6 follicles and >18 follicles. Data suggest that HO donors with high AFC are more efficient in an IVF program following superstimulation because of a possible greater oocyte competence.