Studies on the superovulation and collection of microinjectable embryos in Korean native goats (Capra hircus aegagrus) = 한국 재래산양에서의 과배란유기와 외래유전자 주입에 적합한 수정란의 회수에 관한 연구

Abstract

his study was carried out to determine the hormone treatment scheme for an efficient superovulation and optimal recovery time for obtaining pronuclear embryos suitable for DNA injection in Korean native goats. For a superovulation, FSH(5.6mg) was given over four days in twice daily injections with (FSH/hCG group) or without(FSH group) hCG(100 IU) co-injection at the time of 7th FSH injection. Estrus cycle was synchronized by norgestomet ear-implantation for 11 days and its removal at the time of 6th FSH injection. Among the treated goats, the percentage of ovulated goats, which were examined at 70 to 76 h following implant removal, was greater in FSH/hCG group than in FSH group (100% vs 36.4%) but there was no significant difference in the mean numbers of ovulation points and fertilization rates between the two groups. To optimize hCG treatment scheme and recovery time, we injected hCG at the time of 7th (FSH/hCGa) or 8th(FSH/hCGb) FSH injection and then examined the developmental stage of the embryos recovered at different times after implant removal. In FSH/hCGa group, significant portions(31 to 44%) were beyond 1-cell stage, which was non-injectable, irrespective of their recovery time. However, in FSH/hCGb group recovered at 70 to 76 h after implant removal, great portions(69%) were fertilized and most of them(96.6%) were injectable 1-cell stage. Considering together the fertilization rate and developmental stage of recovered embryos, it is recommendable to administrate hCG at the time of final 8th FSH injection and collect the embryos at 70 to 76 h after implant removal to obtain injectable embryos as many as possible in Korean native goats.