抄録
Embryo transfer technology allows the donor mare to potentially produce multiple foals in a year. In Japan, there has been no report of foal born through embryo transfer after artificial insemination using frozen semen. The aims were to develop a special riding crossbred horse and multiply its number through embryo transfer technology. In both donor and recipient mares, luteolysis was induced by administration of 0.1 mg PGF2α analogue to synchronize the onset of estrus, and ovulation was induced by administering 2000 IU of hCG. Frozen semen from an Irrish Connemara pony was used to breed a Hokkaido native pony by deep-horn artificial insemination (dose, 400 × 106 sperms). A non-surgical transcervical procedure was used to collect embryo from the uterus of the donor mare at day 7 post-ovulation and transferred fresh into the uterus of recipient mare. Weekly blood sampling for monitoring pregnancy associated hormones and transrectal ultrasound for observing fetal development were done throughout the pregnancy. Four embryos were collected from a single donor mare and were transferred to recipients in spring 2018. Three out of 4 recipient mares (75 %) established successful pregnancy and 2 of them have already delivered a healthy foal each in late April 2019, another recipient is expected to give birth in around 1 month. A normal progesterone and equine chorionic gonadotropin hormone profile were observed during the gestation in all recipient mares. This are the first foals produced through embryo transfer in Japan after artificial insemination using frozen semen. We are expecting that this new crossbred (Connemara pony x Hokkaido native pony) would be an ideal riding breed for disable people.
