This study was conducted to investigate the variation of growth characteristics and reproductive physiology in cloned Hanwoo male calves during growing stage. The hematological parameters, body weight, and plasma hormonal levels, birth to 12 months, were analyzed in the cloned calves (n=3). Differences among treatment means were determined by a student t-test. A probability of P<0.05 was considered statistically significant. The hematological parameters, such as white blood cell, red blood cell, and platelet, were not different in both normal and cloned calves. The difference of body weight, however, was significantly higher in the cloned calves, months (p<0.05) and months (p<0.01), than that of the comparators, respectively. The plasma IGF-1 level was statistically significant in the cloned calves, months, compared to that of the normal calves (p<0.05). However, the plasma testosterone level was not different in both normal and clone calves according to growing stage. Taken together, the cloned Hanwoo male calves are growing faster and maintaining a normal reproductive physiology.

본 연구는 체세포 복제 한우 송아지의 생산에서 생시체중과 생존성과의 관계에 대하여 살펴보고자 실시하였다. 293두의 한우 대리모에 580개의 복제란을 이식하였다. 복제란의 임신율은 이식 후 50일까지 72.3%로 높았으나, 이후 급격하게 감소하였다. 평균 임신 기간은 복제 송아지에서 287일(279~295일)이었으며, 인공수정 송아지도 287일(255~293일)로 각각 나타났다. 복제 송아지의 생시체중(30.3kg)은 인공수정 송아지(23.7kg)에 비하여 유의하게 높은 것으로 나타났다(p<0.05). 자연분만(n=17, 29.9kg)과 제왕절개(n=14, 32.3kg)로 태어난 복제 송아지의 생시체중은 차이가 없었다. 하지만, 생후 175일 이전에 사망한 복제 송아지(n=18, 32.8kg)의 생시체중이 175일 이상 생존한 복제 송아지(n=11, 28.3kg)보다 유의적으로 높게 나타났다(p<0.05). 흥미로운 점은 생시체중이 15kg 이하(n=5) 또는 35kg 이상(n=9)인 복제 송아지들은 모두 생후 175일 이전에 폐사하였다. 생후 175일 이전에 폐사한 복제 송아지들(n=20)의 사망 원인은 미성숙 개체 2두(10.0%), 폐와 간 이상 2두(10.0%), 폐의 원인 4두(20.0%), 기형 4두(20.0%), 출생 후 급사(sudden death syndrome) 4두(20.0%) 및 기타 원인불명이 4두(20.0%) 등으로 분류되었다. 이상의 결과를 종합하여보면, 복제 송아지의 정상 생시체중이 6개월 이상을 생존하는데 가장 중요한 요소들 중의 한 가지임을 확인하였다.

Cloned calves derived from somatic cell nuclear transfer (SCNT) have been frequently lost by sudden death at 1 to 3 month following healthy birth. To address whether placental anomalies are responsible for the sudden death of cloned calves, we compared protein patterns of 2 placentae derived from SCNT of Korean Native calves died suddenly at two months after birth and those of 2 normal placentae obtained from AI fetuses. Placental proteins were separated using 2-Dimensional gel electrophoresis. Approximately 800 spots were detected in placental 2-D gel stained with coomassie-blue. Then, image analysis of Malanie III (Swiss Institute for Bioinformatics) was performed to detect variations in protein spots between normal and SCNT placentae. In the comparison of normal and SCNT samples, 8 spots were identified to be up-regulated proteins and 24 spots to be down-regulated proteins in SCNT placentae, among which proteins were high mobility group protein HMG1, apolipoprotein A-1 precursor, bactenecin 1, tropomyosin beta chain, H+-transporting ATPase, carbonic anhydrase II, peroxiredoxin 2, tyrosine-rich acidic matrix protein, serum albumin precursor and cathepsin D. These results suggested that the sudden death of cloned calves might be related to abnormal protein expression in placenta.

The development potential of bovine somatic cells was evaluated using nuclear transfer. A single donor cell derived from fetus of HanWoo(Korean Native Cattle) was selected and deposited into perivitelline space of each enucleated oocyte before electrical fusion and activation. Nuclei of donor cells starved for 7 days (37%) tended to support the development of reconstitute embryo the blastocyst stage better than those of donor cells starved 3, 14 and 30 days. The cleavage rate was significantly lower(P<0.05) in reconstitute embryos derived from large size donor cells(51.2%), than those from small medium size donor cells(76.6 and 73.5, respectively). The developmental rate to blastocyst of reconstructed embryos from medium size donor cells was higher than those from small and medium size donor cells. This study demonstrates that an appropriate culture period for induction into quiescent stage and the size of donor cells effect on the efficiency of nuclear transfer using cultured bovine cells.