본 연구에서는 유전적 가치가 높은 가축을 OPU 기술을 이용하여 단기간에 반복적이고 연속적으로 생체 내 난포란을 채란하여 수정란을 생산할 수 있는 가능성을 연구한 것으로써, 수정란의 안정적인 생산 및 이식으로 가축 개량의 세대 간격을 단축하기 위해 우수한 유전력을 가진 염선된 개체의 임신 초기 3개월 동안에 반복적인 수정란 생산 가능 여부를 조사하였다. 1. 비임신우 및 임신 초기우에 2회/주 채란으로 비인신우에서는 68회 채란으로 생성된 난포수는 72

A combined technology of transvaginal ovum pick-up(OPU) system with in vitro-oocyte manipulation technique can be used for improving reproductive efficiency in the cattle. The objective of this study was to establish a newly-conceived breeding program using OPU in the pregnant cows. The OPU trial was performed in pregnant cows every 10 days from 40 through 90 days of artificial insemination (Al), and number of follicles in ovary, number of retrieved oocytes and embryo development following in vitro-fertilization, were evaluated. Reduced number of follicles in the ovaries of pregnant cows was firstly detected from 70 days after A' and a significant (P<0.05) decrease in the follicle number (5.4 follicles /donor) was found at 90 days than at 40, 50, 60 and 80 days after Al (8.0~9.2). A similar pattern was also observed in the number of oocytes retrieved by OPU apparatus during experimental period. When retrieved oocytes were matured and inseminated in vitro with frozen bull semen, development of the oocytes to the blastocyst stage was not significantly affected by the retrieval time. Four embryos (morula or blastocyst stage) derived from oocytes retrieved from pregnant cows were nonsurgically transferred to four recipient cows on day 7 of estrus cycle. For the first time in Korea, three of four transferred embryos developed to live calves with normal physiological parameters. In conclusion, an effective breeding program employing pregnant cow can be developed by use of OPU trial and in vitro culture techniques of oocytes ; OPU system could be repeated in pregnant cows with no risk of abortion and viable offsprings were borne after transfer to the recipients.