Anti-Müllerian Hormone and OPU-ICSI Outcome in the Mare

SIMPLE SUMMARY: The in vitro production of equine embryos, using ovum pick-up (OPU) and intracytoplasmic sperm injection (ICSI), is gaining popularity for breeding sport horses. However, the results of this complicated procedure are variable and hard to predict. Therefore, the aim of this study was to evaluate anti-Müllerian hormone (AMH), a factor which has been linked to reproductive success in human and cattle, as an indicator of the OPU-ICSI outcome in horses. Therefore, for 103 mares subjected to commercial OPU-ICSI, the AMH level was measured in the blood at the moment of OPU and linked to the number of oocytes and embryos produced by ICSI. We found that mares with a high level of AMH gave rise to a better oocyte collection and a higher number of embryos. However, since mares with a low AMH value could also produce embryos, a single measurement of the AMH in the blood is not sufficient as an independent predictor of the OPU-ICSI outcome in the horse. ABSTRACT: Anti-Müllerian hormone (AMH) reflects the population of growing follicles and has been related to mammalian fertility. In the horse, clinical application of ovum pick-up and intracytoplasmic sperm injection (OPU-ICSI) is increasing, but results depend largely on the individuality of the mare. The aim of this study was to assess AMH as a predictor for the OPU-ICSI outcome in horses. Therefore, 103 mares with a total follicle count above 10 were included in a commercial OPU-ICSI session and serum AMH was determined using ELISA. Overall, the AMH level was significantly correlated with the number of aspirated follicles and the number of recovered oocytes (p < 0.001). Mares with a high AMH level (≥2.5 µg/L) yielded significantly greater numbers of follicles (22.9 ± 1.2), oocytes (13.5 ± 0.8), and blastocysts (2.1 ± 0.4) per OPU-ICSI session compared to mares with medium (1.5–2.5 µg/L) or low AMH levels (<1.5 µg/L), but no significant differences in blastocyst rates were observed. Yet, AMH levels were variable and 58% of the mares with low AMH also produced an embryo. In conclusion, measurement of serum AMH can be used to identify mares with higher chances of producing multiple in vitro embryos, but not as an independent predictor of successful OPU-ICSI in horses.