186 Evaluating equine oocyte transportation techniques: a comparative study of maturation, cleavage, and blastocyst rates in Equitainer, MicroQ, and incubator systems

The use of ovum pickup (OPU) and intracytoplasmic sperm injection (ICSI) is expanding in the equine industry, overcoming various reproductive challenges and improving breeding efficiency. The cumulus–oocyte complexes (COCs) are often held for scheduling purposes or transported from the collection site to an ICSI laboratory, without any detrimental effects on the developmental competence of the oocytes. Currently, there are different methods for the oocyte shipment/holding to keep a constant holding temperature regardless of the outside environment. This study investigates the efficacy of three widely used oocyte holding and shipment methods within a commercial OPU-ICSI program: the Equitainer, the MicroQ system, and digital incubators. A total of 3635 COCs were aspirated and either held in an incubator at a set temperature of 22°C (n = 465) for 18 h, or the COCs were shipped overnight to the ICSI laboratory using either an Equitainer (n = 541) or MicroQ device (n = 2629). Temperature fluctuations were monitored during transportation in the Equitainer and MicroQ with a temperature logger every 10 minutes, while the minimum and maximum temperatures were recorded in the digital incubator. The minimum temperatures in the Equitainer, MicroQ, and digital incubator were 18.49°C, 19.13°C, and 22.0°C, respectively. The median maturation rates of 43%, cleavage rates of 50%, and blastocyst rates of 33% were achieved using Equitainer. The MicroQ system, equipped with battery-powered temperature control, thus more expensive, showed a median maturation rate, cleavage rate, and blastocyst rate of 60%, 67%, and 23%, respectively. The digital incubator, though used solely for holding and not transportation, provides a controlled and steady environment conducive to oocyte development, with maturation, cleavage, and blastocyst rates of 60%, 71%, and 25%, respectively. In terms of the maturation rate, both the MicroQ and incubator outperformed the Equitainer, as shown by the Wilcoxon and Dunn post hoc tests (P < 0.0001 and P = 0.001, respectively). The MicroQ also recorded a higher cleavage rate compared with the Equitainer (P = 0.001). There was no statistical difference observed in the blastocyst rates among the groups. However, a higher maturation rate entails that more oocytes were injected; thus, more blastocysts were produced (proportionally) compared with the Equitainer, as blastocyst is calculated based on the number of injected oocytes. Thus, our data suggest that the MicroQ device provides optimal conditions for oocyte transportation.