The present study was carried out to investigate the effects of co-culture cells and growth factors on in vitro culture of Korean native cattle(KNC) embryos fertilized in vitro. Two-eight cell embryos were cultured in vitro using 4 types of co-culture cells and 3 growth factors singly or in combination. The results were as follows, In the co-culture of 2~8 cell embryos with bovine oviductal epithelial cell(BOEC), granulosa cell(BGC), uterine epithelial cell(BUEC) and mouse embryonic fibroblast (MEF) monolayers, the developing rate to blastocysts was significantly(P<0.05) higher with BUEC(32.1%) than with MEF(15.3%), BGC(13.2%) and non co-culture control(11.6%). When the morula co-cultured with BOEC for 5 days following in vitro fertilization were co-cultured with BOEC continuously or with BUEC, respectively, the developing rate to blastocysts was higher with BUEC(73.9%) than with BOEC(56.0%). To examine the effects of growth factors on in vitro development of 2~8 cell embryos, epidermal growth factor(EGF), transforming growth factor-l(TGF-l) and insulin-like growth factor-1(IGF-1) were added singly or in combination to TCM 199 maturation medium with respective concentration. In a addition of each 10, 30 and SOng /rnl EGF, the developing rate to blastocysts was the highest in lOng /ml EGF(25.3%). In addition of each 1, 2 and Sng /mi TGF-1, the developing rate to blastocysts was the highest in lng /ml TGF-1(28.8%). In addition of each 50, 100ng/ml JGF-l, the developing rate to blastocysts was higher in 100ng/ml IGF-l(16.5%) than in SOng/mi IGF-1(12.9%). When lOng /ml EGF and lng /ml TGF-l was added singly or in combination, the developing rate to blastocysts was similar in groups added singly or in combination with EGF and TGF-l (23.l~24.6%), although higher than in control(16.7%). In the co-culture of 2~8 cell embryos Wth BOEC + each 10, 30 and 5Ong /rnl EGF, the developing rate to blastocysts was significantly(p<0.05) higher in BOEC + long /ml EGF(32.3%) than in BOEC + 3Ong /ml EGF(18.9%) and BOEC + song /ml EGF(9.7%). In the co-culture of 2~8 cell embryos with BOEC + each 1, 2, Sng /ml TGF-l the developing rate to blastocysts was higher in BOEC + Sng/rnl TGF-l(28.2%) than in BOEC + lng /ml TGF-l(21.7%) and BOEC + 2ng/ml TGF-l(21.4%). In summary, higher developing rate to blastocysts were obtained with co-culture of BUEC for co-culture system, with addition of lOng /ml EGF or lng /ml TGF-l for growth factor culture system, and with co-culture of BOEC + lOng /ml EGF or BOEC + Sng /ml TGF-l for co-culture + growth factor culture system.

The object of this study was to evaluate the effect of uterine epithelial cells on development of Korean native cattle(KNC) oocytes fertilized in vitro. Qocytes were collected from ovaries of slaughtered Korean Native Cows and matured in TCM199 with granulosa cells supplemented with 10% FBS, 5g/ml FSH, 10 JU/ml hCG, and 1g/ml estradiol-17 for 24 hrs. For co-culture of in vitro development of fertilized ova, oviductal epithelial cells (ll0˚cells /ml) obtained from slaughtered cow and uterine epithelial cells(110˚cells /ml) flushed from the superovulated holstein on Day 7 were incubated in 39, 5% , 95% air. Frozen-thawed KNC sperm was capacitated with BO(Brackett & Oliphant, 1975) medium supplemented with 10mM, 5mM-caffein. Matured oocytes were inseminated for 20 hrs. And then fertilized oocytes were washed with culture medium and transferred to oviductal epithelial cells for in vitro development and three days later a portion of embryos were transferred to uterine epithelial cells. Stastical methods of developmental rates on KNC-IVF oocytes was ANOVA-test. Developmental rates of KNC-IVF oocytes was significant higher(P<0.01) when co-cul-tured with uterine epithelial cells(25.2%) than oviductal epithelial cells. Blatocyst cul-tured for 7 to 9 days were frozen by automatic freezer with 1.4M glycerol-PBS. Survival rates of blastocyst was 40.0%. Fourteen frozen-thawed blastocysts were transferred to five holstein heifers on day 7 after natural estrus. Three recipients were observed twin and one recipient was single by ultra-sound systems on days 45 after embryo transfer.

This study was carried out to compare farrowing rate and litter traits for European and American lines with boar sperm frozen in straws. Farrowing rate, litter size and mean pig weght at birth and 21 days were investigated. A total of 36 gilts Landrace, Large white and Duroc were investigated at the Chungnam Provincial Animal Breeding Station. We obtained higher farrowing rate and litter traits for European line boars compared to American line boars.

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.

The objective of this study was to produce calves derived from in vitro fertilization of in vitro matured follicular oocytes. Oocytes aspirated from small antral folicles of ovaries obtained at a local slaughter house were matured and fertilized in vitro. At l8hrs after insemination with Korean native cattle semen, oocytes were co-cultured for 6~7 days by utilizing co-culture system with bovine oviduct epithelial cell. After co-culture, good or excellent quality late morulae or early blastocysts were selected by morphological criteria under stereo microscope. Selected embryos were transferred to recipients on day 6 or 7 (estrus = day 0). Recipients were monitored by observation for estrus and rectal palpation after 60 days from embryo transfer. One of them went to term with the birth of a calf. This case is the first production of calf derived from in vitro fertilization in Korea.

This study was carried out to propagate Korean native cattle using beef recipients by embryo transfer. Seven Korean native cattle donors were superovulated with FSH 32mg and Embryos collected from donors were frozen and preserved in National Animal Breeding Institute. Frozen-thawed embryos were transferred to synchronized 40 beef recipients nonsurgically in Daekwanryeong Branch of National Animal Breeding Institute. The results obtained were as follows : 1. Total ova and transferable embryos per donor were 11.4 and 11.1 from 7 donors, respectively. 2. Among 40 recipients transferred with frozen-thawed embryos, 20 were pregnant(50.0%). 3. The pregnancy rate according to time from embryo thawing to transfer was higher when transferred within 3 hours than after 3 hours(57.6% vs. 14.3%). 4. The cow recipients showed slightly higher pregnancy rate than the heifer(53.3% vs. 48.0%). 5. Two grade embryos showed higher pregnancy rate than 1 grade(66.7% vs. 45.2%).

Effects of caffeine, heparin and caffeine-heparin treatments for in vitro capacitation of Korean Native Cattle sperm on acrosorne reaction and viability were studied using the methods of Wells-Awa and Dual stain. The results were summerized as follows: 1. The acrosome reaction of sperm when treated with caffeine after 0 to 4 hrs of preincubation were 11.0~75.7% for Wells-Awa stain, and 14.3~75.55% for Dual stain. True acrosome reaction of sperm for Dual stain was 3.0~29.2%. The viability of sperm was 62. 2~27.2%. 2. The acrosome reaction of sperm when treated with heparin after 0 to 4 hrs of preincubation were 17.0~81.2% for Wells-Awa, and 14.3~75.5% for Dual Stain. True acrosome reaction of sperm for Dual stain was 1.5~26.6%. The viability of sperm was 58.6~35. 8%. 3. The acrosome reaction of sperm when treated with caffeine-heparin after 0 to 4 hrs of preincubation were 13.0~83.2% for Wells Awa, and 11.0~78.5% for Dual stain. True acrosome reaction of for Dual stain was 5.1~26.3%. The viability of sperm was 60.5~30.1%.

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%).

본(本) 연구(硏究)는 한우육용화(韓牛肉用化) 개량(改良)에 있어서 가장 중요한 경제형질(經濟形質)인 체중에 대(對)한 유전적개량량(遺傳的改良量)을 최대(最大)로 증대(增大)시킬 수 있는 적정규모(適正規模)를 산출(産出)하여 한우(韓牛)의 육용능력(肉用能力)을 조기(早期)에 효율적(效率的)으로 개량(改良)할 수 있는 방안(方案)을 제시(提示)하기 위하여 수행되었다. 체중에 대(對)한 유전적개량량(遺傳的改良量)과 세대별(世代別) 체중평균치의 변화(變化)를 추정(推定)하기 위하여 2재(才)이상의 암소잡균(雜菌)은 매세대(每世代) 675,000두(頭)가 유지(維持)되고 또한 암소는 매년(每年) 15%가 도태(淘汰)된다는 등(等) 몇가지 반정(飯定)아래서 다음과 같은 요인(要因)이 고려(考慮)되었다. 1) 암소 집단중(集團中) 인공수정(人工授精)되는 비율(比率); 30, 40, 50, 60, 70% 2) 종모우(種牡牛) 두당, 년간(年間) 정액(精液) 생산(生産) 수량(數量); 5,000, 7,000, 10,000, 15,000, 20,000두분(頭分) 3) 종모우(種牡牛)의 평균체중; 480, 520, 560, 600, 640, 680, 720kg/18개월령(個月齡)이다. 본연구(本硏究)에서 얻어진 결과(結果)를 요약(要約)하면 다음과 같다. 1) 체중의 유전적개량량(遺傳的改良量)은 이용(利用)되는 종모우(種牡牛)의 체중에 크게 영향(影響)을 받으며 매세대당유전적개량량은 28.66~36.31kg으로 추정(推定)되었다. 2) 유전적개량량(遺傳的改良量)의 80~90%는 종모우선발(種牡牛選拔)에 기인(起因)하는 것으로 나타났다. 3) 종모우(種牡牛)의 평균체중이 매세대(每世代)마다 40kg씩 증가(增加)되고 암소의 인공수정(人工授精)되는 비율(比率)이 50%이상으로 확대(擴大)되어지는 경우 5세대(世代)이후에서 수소 및 암소의 체중평균치는 인공수정집단(人工授精集團)에서는 600kg과 520kg, 그리고 전(全) 모집단(母集團)에 있어서는 560kg과 480kg에 도달될 것으로 추정(推定)되었다.