Studies on the Production of Twins in Cattle

소의 쌍자 생산술 개발에 관한 연구

Induction of twinning was attempted by transfer of two whole- or demi-embryos in Holstein cows and heifers. Cows were superovulated with follicle stimulating hormone(FSH) administered twice daily in intra-muscular injection. On day of 6.5 to 7 post-estrus, embryos were collected nonsurgically, Normal morulae and early balstocysts were obtained from superovulated cows. The embryos were hisected with a micro-blade made from a razor. Twenty seven pairs of half embryos were successfully produced and 23 pairs of half embryos were transferred to recipients( Group A). Twenty cows were treated with low unit of FSH (3mg${\times}$2,2mg${\times}$2 ; Group B1, 2mg${\times}$2, 1mg${\times}$2, 1mg${\times}$2 ; Group 32) to induce double or triple ovulations. The cows of Group B1 and B2 were Inseminated artificially(A1) at following estrus. Twenty four heifers were bred by A1 and received an additional embryo into the uterine horn contralateral to the corpus luteum(CL) 6 days later(Group C). One embryo was transferred into each uterine hem of 16 heifers 6 days after estrus(Group D). Fourteen heifers were received two embryos into the uterine horn ipsilateral to the CL at day 6 of estrous cycle(Group I). Pregnancy rates at 60 days in Group A, B1, B2, C, D and E were 34.8％, 70.0％, 60.0％, 66.7％, 62.5％ and 57.1％, respectively. Twinning rates were 8.7％, 20.0%, 10.0％, 16.7％, 18.7％ and 21.4％, respectively. The present experiments demonstrate that FSH treatment( Group 31) and ipsilateral transfer( Group I ) of two whole-embryos are more useful methods to produce twins than the others.

소에 있어서 효율적인 쌍자생산 방법을 검토하기 위하여 이분수정란의 이식, 저단위 FSH에 의한 다배란 유도후의 인공수정, 인공수정후의 수정란이식, 수정란 2개의 양측 및 단측 자각에의 이식 등의 방범을 적용하여 본 실험을 수행하였다. 각 실험군의 60일 수태율은 각각 34.8%, 65.0%(평균), 66.7%, 62.5%, 57.1%였으며 쌍태임신율은 8.7%, 15.0%(평균), 16.7%, 18.7%, 21.4%였다. 위의 결과에서 볼 때 저단위 FSH 투여법(Group B1)과 수정란 2개의 단측 자궁각 이식방법에 있어 쌍태율이 높게 나타나는 경향이 있었으나 실용적 측면에서는 낮은 수준이었다.