• Reproductive and Developmental Biology
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• v.32 no.1
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• pp.51-58
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• 2008

This study was performed to investigate the relation between birth weight and survivability on the production of cloned Hanwoo calves. The 580 cloned embryos were transferred into the 293 recipients. The pregnancy rate of the cloned embryos was 72.3% at 50 days after embryo transfer, and then the rate was dramatically decreased. The mean gestation lengths were 287 days in both clone (range of$279{\sim}295$ days) and artificial insemination (AI, range of $255{\sim}293$ days) calves, respectively. The mean birth weight of cloned calves (30.3kg) was significantly higher compared to that of AI calves (23.7kg) (p<0.05). Among the cloned calves, the birth weight was not different in both normal delivery (n=17, 29.9kg) and caesarean section (n=14, 32.3kg). The weight, however, was significantly higher in the clones (n=18, 32.8kg) dead within 175 days than that of the clones (n=11, 28.3kg) alive more than 175 days after birth (p<0.05). Interestingly, all cloned calves weighed <15kg (n=5) or >35kg (n=9) at birth have been dead within 175 days from the date of birth. The causes of death in the cloned calves were premature birth (n=2, 10.0%), abnormal function of lung and liver (n=2, 10.0%), abnormal function of lung (n=4, 20.0%), malformation (n=4, 20.0%), unknown (n=4, 20.0%), and sudden death syndrome (n=4, 20.0%), respectively. Our findings suggest that normal birth weight is one of the most important factors to survive more than 6 months in cloned calves.

• Journal of Embryo Transfer
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• v.30 no.3
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• pp.175-181
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• 2015

The objective of this study was to monitor health conditions of genetically identical somatic cells cloned Korean white cattle, endangered indigenous cattle (EIC) and indigenous cattle (IC) by analysis of hematologic characteristics. Naturally ovulated oocytes and donor cells were used for somatic cell nuclear transfer (SCNT). Donor cells and enucleated oocytes were followed by electric fusion, chemical activation and surgical embryo transfer into the oviducts of surrogate females. Two recipients became pregnant; two maintained pregnancy to term, and one live cattle were delivered by caesarean section. The cloned Korean white cattle were genetically identical to the nuclear donor cattle. As a result, the mean values of RBC and platelet of cloned cattle and white cattle were significantly decreased by age (P<0.05). The mean values of RBC, HCT, MCV and MCHC between cloned cattle and IC of the same age (1~2 years) showed the statistical significance (P<0.05). Also, in the WBC of Korean white cattle, the estimated values were decreased according to the age from $12.0{\times}10^3/{\mu}l$ under 1 year to $11.0{\times}10^3/{\mu}l$ over 1 years respectively. Although clone-cattle had lower numbers of RBC than reference range, the most of RBC and WBC related heamatologic results of cloned cattle were not different when compared to reference range. This study suggests that cloned Korean white cattle derived from SCNT did not have remarkable health problems, at least in the growth pattern and hematological parameters. In addition, this study provides a valuable resource for further investigations of the preservation of rare genetic stocks underlying traits of interest in cattle.