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%).

This experiment was conducted to evaluate individual difference of chewing speed and chews per bolus duing the rumination using twenty three heads of grazing cattle and thirty six heads of barn feeding cattle. Rumination behaviour was measured and recorde

Hydrogel chambers made from polymerized 2-hydroxyethyl methacrylate were used for in chamber fertilization. To determine whether sperm motility was preserved in the Hydrogel chamber, chambers which have rabbit sperm or frozen-thawed bovine sperm were transplanted inside of mouse peritoneal cavity and sperm were observed after recovering the chambers in the due time. As a result, it was determined that preservation of sperm motility was good. To determine whether in chamber fertilization was possible, chambers which have rabbit oocytes and sperm were transplanted inside of mouse peritoneal cavity and eggs were observed after recovering the chambers at 84 hr of preservation. As a result, the fact that fertilization and culture was occurred inside of the chamber was determined.

This experiment 'was conducted to investigate the grazing cattle's palatability by the method of grazing time on the pasture dominated orchardgrass and on the pasture dominated perennial ryegrass from June to October, 1987. The experiment was carried out

공란우 89두와 수라우 94두를 사용하여 호르몬 투여에 대한 난소반응, glycerol의 평형과 제거방법에 따른 융해란자의 형태적 정상성과 동결 융해란의 이식후 임신율과 쌍태유기율을 조사하였다. 1. 호르몬처리에 대한 난소반응 :1) 과배란 처리후 배란된 난자수는 A.B.C군에서 각각 8.3, 7.8, 9.5개로서 C군이 전체 평균의 8.3개보다 증가되었다. 2) 난자의 회수율은 42.1%, 두당회수된 난자수는 3.5개였으며, 회수란자중 정상발육한 상실

These studies were conducted to investigate the effect of repreated superovulation on embryo production, the effect of the frozen-thawed embryos transferred on the developmental stage and grade, and donor-recipient synchrony on pregnancy rate in Korean native cattle. The results obtained in these studies were as follows: 1. Repeated superovulations in Korean Native Catile were not affected on the number of corpus luteum (CL), embryos recovered and embryos cleaved (range: 4.8 4.21 to 9.5 6.50, 1.8 2.53 to 8.2 8.04 and 1.6 2.32 to 4.0 4.59, respectively). 2. Blastocyst embryos (38.5%) showed higher pregnancy rate than morula (31.6%). 3. The pregnancyrates of cattle transferred with good and fair embryos were 33.3% and 40.4%, respectively. 4. The pregnancy rate when the donors exhibited estrus 12 hours earlier than the recipients (62.5%) was higher than when the donors and recipients exhibited estrus at the same time (33.3%) or when the donors exhibited estrus 12 hours later than the recipients (20.0%).

This study was carried out to produce the antisera for the blood typing in cattle. Blood types of eighty cattle were previously determined by 56 kinds of internationally standardized antisera from Japan. The donorrecipient animal arrangements were determined according to tile previously determined blood types of animals by the computer program SS-l for efficient production of antisera. Six kinds of standard antisera, H,B', 12, C2, Z, U2, were produced by isoimmunirzation and absorption methods.

When the dairy cattle are genetically improved by embryo transfer, generation intervals can be reduced since sires are selected by their full-sister's records rather than by their daughter's records and selection intensity increases because only donor cows and sires for them are selected. In addition by embryo transfer many number of full-sisters and full-sisters are produced at the same time, resulting in the increase in the accuracy of selection.