This study was carried out to establish an effective embryo production system by analyzing several factors ifluencing in vivo embryo production in Hanwoo. The results are summarized as follows : 1. The number of total, fertilized and transferble embryos by gonadotropins were no significant difference among PMSG, FSH and FSH+PMSH. 2. The numbers of recovered and transferable embryos by type of FSH were no significant difference in both FSH-P and FOLLTROPIN-V but significant difference with SUPER-OV(p<0.01). 3. The numbers of recovered and transferable embryos by age of donor were highest in 5 years old. 4. The recovered number of transferable embryos was highest in the cows at the 1 st and 3rd parity but significantly lower in hifers and the cows at more than 6th parities(p<0.01). 5. The numbers of trasferable embryos by postparient were more<270 days than > 270 days in significant difference(p<0.01). 6. Embryo production after treatment of repeated super ovulation was no significant difference. 7. Recovered and trasferable embryos production after treatment of repeated super ovulation interval was highest 81∼100 days and significant difference(p<0.01). 8. The numbers of recovered and transferable embryos by seasons were no significant difference.

본 연구는 한우 다배란처리시 노동력을 절감하고 공란우의 스트레스를 방지하여 정상수정란을 안정적으로 생산할 수 있는 1회 주사시 FSH의 용해제의 종류와 농도를 선정하기 위하여 다양한 용매제에 용해시킨 1회 주사와 기존의 다회주사에 의한 난소반응을 비교 검토하였다. 1. 공란우에 다배란 처리후 발정유기는 처리 1과 7에서 100% 유기되었다. 2. 채란수와 정상수정란 수는 처리 1과 처리 7에서 (3.5, 2.9와 3.8, 3.5) 다른 처리구에 비해 유

The present study was carried out to investigate effect of FSH -P dose and energy level on normal embryo production after superovulation in Hanwoo. The results obtained were as follows ; 1. There was a significant effect of dose of FSH-P on normal embryo production in Hanwoo(P5.9), 40(4.9i5.7), 50mg(2.22.6). 2. The plasma P levels on the first treatment day were higher group( >4ng /ml) than lower group( <=4ng /ml), produced significicantly(P<0.05) higher number of normal embryos. 3. There was a significant effect of energy level on normal embryo production in Hanwoo(P6.0), number of normal embryos were higher than TDN 70%(5.16.5) and TDN 130%(4.42.6) 4. The donor returned to normal estrus after superovulation were 44.8, 28.4 and 29.9 days by TDN 70, 100 and 130%, respectively.

The objective of this study was to enhance the pregnancy rate of repeat-breeder Hanwoo with gonadotropin-releasing hormone(Gn-RH) at the time, dose and site of administration.The results obtained were summaried as fallows:1.Ovulation time and pregnancy rate following GnRH administration time was 46.0, 27.4, 42.0 and 43.2hr and 33.3, 57.1, 37.5 and 40.0% at non-treatment, estus, 1st A' and 2nd Al treatment, respectively.2. Ovulation in repeat-breeder was induced 100% within 24hr with GnRH administration at the time of estrus.3. Ovulation time and pregnancy rate following GnRH adminstration dose and site was 25.2, 32.6, 17.6 and 27.6hr, and 28.6, 42.9, 75.0 and 66.7% at 50g+IU, 50g+IM, 100g+IU and 100g+IM treatments, respectively. It is concluded that GnRH administration for repeat-breeder was enhanced the pregnancy rate when treated with 100g intrauterine at the time of estrus.

This study was carried out to produce monozygotic twin calves by transfer of bisected embryos. Four Korean native cattle donors were superovulated with FSH and flushed to collect embryos on day 6 or 7 of the estrus cycle. Morula and early blastocyst embryos showed 1 or 2 grade were bisected with microblade and each set of demi-embryos without zona pellucida were transferred nonsurgically to 10 recipients respectively. The results obtained were as follows; 1. Twenty four demi-embryos (92.3%) were separated from 13 original embryos and among them 20 demi-embryos (83.3%) had normal appearance without severe damage. 2. Four sets of fresh demi-embryos were transferred to 4 recipients and one recipient was twin pregnant 3. Six sets of frozen-thawed demi-embryos were transferred to 6 recipients. Two recipients were pregnant, one of them twin.

This study was carried out to produce superior dairy cattle by embryo transfer. Seven dairy cows were superovulated with divided injection of FSH 4Omg for 5 days started on day 9 to 14 of the estrus cycle and injection of PGF 45mg on day 4 of FSH injection. Donor cows were flushed to collect embryos on day 7 or 8 of the estrus cycle. Fresh embryos collected were transferred to synchronized dairy recipients or frozen using glycerol 3 step method to he equilibrated. And 35 embryos which were frozen using glycerol 6 step method were imported from U.S.A. After glycerol dilution of frozen embryos was done by reverse density during freezing. frozen-thawed embryos were transferred to synchronized dairy or beef recipients. The results obtained were as follows; 1. Total of 24 embryos were collected from 7 donor cows flushed and transferable embryos were 18 (75.0%). 2. Among 24 embryos. morula, early blastocyst, blastocyst, expanded blastocyst and unfertilized ova were 3 (12.5%), 1 (4.2%), 10 (41.6%), 4 (16.7%) and 6 (25.0%), respectively. 3. Heat inducing rate after 1st and 2nd injections of PGF in Holstein and beef cattle was 83.3% and 71.4% and 62.5% and 69.2%, respectively. 4. Among 56 recipients, 23 head were pregnant (41.1%). The pregnancy rate of fresh embryos was 50.0% (1/2 heads) and the pregnancy rate of frozen embryos which were frozen using glycerol 3 step and using glycerol 6 step imported from U.S.A. was 52.6%(l0/19 heads) and 34.3%(12/35 heads), respectively. 5. The pregnancy rate of blastocyst (60.0%) was higher than that of morula (39.0%), early blastocyst (25.0%) and expanded blastocyst (0%). 6. The pregnancy rate of grade I embryos (52.2%) was higher than that of grade 2 (34.6%) and grade 3 (28.6%). 7. The pregnancy rate according to synchrony of recipient with donor was higher in simultaneous recipient (55.0%) and +l2hrs' (53.8%) than -24hrs' (23.5%), -l2hrs' (20.0%) and +24hrs' (0%).