Optimizing equine assisted reproductive technologies

Application of assisted reproductive technologies (ARTs) is more common in the horse breeding industries, but there is still room for improvement. Embryo recovery rate after embryo flushing, embryo production rate after ovum pick-up (OPU) and intracytoplasmic sperm injection (ICSI), cryopreservation of equine embryos and pregnancy rates after transfer of these embryos can be improved. ARTs cause epigenetic changes in the early embryo, resulting in low birth weight in man and large offspring syndrome in cattle. It is unknown how this alter equine fetal development. Ultrasonographic evaluation of fetal development throughout gestation can help to monitor and detect abnormal development. Fetal growth curves of Dutch Warmblood mares are created as baseline for future monitoring of intrauterine development of foals produced by ARTs. Only aorta diameter and biparietal cross-sectional surface area increased linearly during late gestation. Mitochondria are one of the factors involved in success of fertilisation and early embryonic development. In vitro embryo production (IVEP) and maternal age affect mitochondria in oocytes and embryos by reducing their numbers and functionality. In this study it became evident that day (D) 7 embryos from older (>16 years) mares contain fewer mtDNA copy numbers than embryos from younger (