This study was carried out to produce twin calves by embryo transfer in Hanwoo and investigate the pregnancy and twin rate by recipient's conditions. All recipients were bred at estrus by artificial insemination with Hanwoo semen and then transfered an additional embryo produced in vivo or in vitro to tbe uterine horn contralateral to the corpus luteum on Day 7. The results obtained were as follows ; 1. The pregnancy rate was higher in young recipients of 3 years (68.8%) than in old ones of 10 years and greater(36.4%). And for CL size pregnancy rate was 57.9, 45.4 and 60.1% in large, medium and small size of CL of recipients, respectively. 2. 447recipients were transferred an additional embryos at 7th day after Al and average pregnancy rate was 57.5% and twin production rate was 22.2%. 3. Average pregnancy and twin production rate by direct transfer methods of frozenthawed IVF embryos was 56.0 and 16.7%. 4. The ratio of male to female twin in a total of 55 twin pairs was 54.6%, and average gestation lengths of male to female and female to female twin were 280.65.4 and 279.715.4 days, respectively. Average birth weight of twins was beavior in male and male twin(23.2i5.8kg) than in male and female twin(20.52.6kg).

This study was carried out to investigate the effect of sperm concentration of 5ml maxi-straw on farrowing rate and number of pigs born alive per litter in deep frozen boar semen. We did not find out the effect of sperm concentration on post-thaw sperm motility and NAR acrosome. However, farrowing rate and number of pigs born alive per litter of 7. 5 x 10˚ /5ml and 10.0 x 10˚ /5m1 sperm concentrations were higher than those of 5. 0 /10˚ /5ml sperm concentration.

These experiments were carried out to determine the effect of pregnancy in bisected embryo. The embryos of ICR mouse were microsurgically bisected at morula and blastocyst stage using microsurgical blade attached a micromanipulator. These bisected embryos without zona pellucida were cultured up to blastocyst stage and cell count and diameter of stained blastomere, and transferred pseudopregnant mice. And the development of these bisected embryos was compared with the results of production of young of the corresponding intact embryos or cell stage. When the bisected mouse embryos were cultured in vitro for 20 to 24 hours in morula stage(77.2%) or 3 to 6 hours in blastocyst stage(84.1%), them were developed to the expanded blastocyst stage. There were no significant(P<0.05) differences in the development rate of bisected embryos between in morula and blastocyst stages. The embryo size of blastocyst developed in vitro from bisected embryo was small(P<0.05)than intact embryo. However, the number of blastomeres with bisected embryo (24.7+1.3and 21.5+1.2 respectively) were significantly(P<0.05) reduced, compared with that of intacted embryos(36.3+1.1 and 41.4+1.2 respectively). When compared with the result of pregnancy rate(63.6%) after surgical transfer of bisected morulae, a similar result(65.4%) was obtained with bisected blastocyst stage(P< 0.05). However, production of youngs (38.8%) after transfer of bisected morula, a similar result (38.1%) was obtained with bisected blastocyst stage (P<0.05).

This study was carried out to investigate the seasonal effect on the recovery rate of embryos in donors and on the conception rate in recipients following embryo transfer. The results obtained from this experiment were summarized as follows: 1. The ovulation point in winter and summer was 28.6 and 28.6, respectively. There was no difference in ovulation point between two seasons. More embryos recovered in the winter (27,0) than the summer (20.9). 2. The number of CL, unruptured follicle, hemorrhagic follicle, young born and pregnancy rate in the winter were 6.0,4.8,1.5,1.8 and 75%, and those in the summer were 2.9,5.7, 3.8, 2.2 and 46.7%, respectively. The rate of synchronization of recipients in the winter showed better results than that in the summer.

수정란이식에 있어서 수란우의 조건에 따른 수태율을 조사하기 위하여 생수 14 ~24개월되는 젖소 처녀우 29두와 한우 처녀우 1두, 그리고 젖소 경산우 3두 계33두의 수란우에 morulae stage부터 advanced blastocyst stage의 수정란을 각각 1개씩 이식하여 이들 수란우의 연령, 이식된 계절, 반복사용 그리고 공란우와 수란우간의 발정동기화 시차 등에 따른 수태율을 조사하였으며 그 결과를 요약하면 다음과 같다. 1. 수란우의 연령에 따른 수태율은 경산우가 100%로 좋았고 18개월 이상의 처녀우가 78%로 높았다. 14개월 이하의 어린 처녀우가 가장 나쁜 67%를 보였다. 2. 이식한 계절에 따른 수란우의 수태율을 보면 겨울(11월~1월)과 봄(2월~4월)이 각각 100%, 83%로 가을(8월~10월)의 50%보다 좋았다. 3. 1차 이식 후 불임된 수란우의 재사용에 따른 수태율은 1차에 사용된 31두 수란우 중 25두가 수태, 80.7%의 수태율을 보였으나 2차례 이용된 2두는 모두 임신되지 못했다. 4. 공란우와 수란우의 발정동기화의 시차에 따른 수태율은 -(before donor) 12 시간, -6 시간, +(after donor) 6시간, +12 시간, 그리고 +12시간 이상에서 각각 100%, 86%, 67%, 79% 그리고 50%로 공란우보다 빠른편이 수태율이 늦은 우군보다 높았고 시간 이내의 동기화된 우군에서 좋은 수태율을 보였다.

This study was carried out to investigate the inte actions between recipients and embryos to compare pregnancy rates in bovine embryo transfer, such as synchrony and stage of embryos, synchrony and quality of embryos, synchrony and side of uterine horn, and preservation time and stage of embryos. Fifty-two embryos were transferred by surgically to 42 Holstein heifers, 3 Holstein cows and 7 Korean native heifers from Feb., 1985 to June, 1986. The results were as follows: 1. In the trial of interactions between synchrony and embryo stage, recipients synchronired from- hours to + 12 hours in synchrony and embryos from morulac stage to advanced blastoctyst stages showed reason able pregnancy rate. 2. Excellant (A) and good (B) grade embryos showed good pregnancy rate, 81.8% and 73.3% respectively, but fair (C) grade embryos showed poor, 25% only at the same boundary of recipient synchrony. 3. More recipients had corpus luteum on the right ovary than the left, and also had better pregnancy rate (26/32 vs 13/20,81.3% vs 65%). 4. A good pregnancy rates (over 60%) were obtained with the embryo transferred 17hrs after flush at room temperature or field condition in culture medium.

수정란 이식의 성공적 수행을 위해서는 양질의 수정란 생산, 영양상태가 양호한 수란우의 선발, 수정란과 수란우의 발정동기화, 황체발육이 양호한 수란우의 선발과 숙련자에 의한 수정란의 이식 등의 제반사항이 최적으로 이루어 졌을 때에 가능하다고 사료된다. 특히 수란우의 영양상태는 각양각색이라 판단하기가 어렵다. 따라서 본 연구에서 수란우의 사양관리 형태가 수란우 선발율과 수태율에 미치는 영향을 조사하여 수정란 이식의 효율증진을 도모하고자 실시하였다. 본 실험