79 RELATIONSHIPS BETWEEN SURVIVAL RATE AND BIRTH WEIGHT IN CLONED KOREAN NATIVE CALVES
B.C. Yang A , G.S. Im A , D.H. Kim A , S.K. Lee A , H.S. Park A , H.H. Seong A , J.K. Jung A , W.K. Chang A and K.N. Kim ANational Livestock Research Institute, RDA, Suwon, Korea. email: ddoddo@chol.com
Reproduction, Fertility and Development 16(2) 161-161 https://doi.org/10.1071/RDv16n1Ab79
Submitted: 1 August 2003 Accepted: 1 October 2003 Published: 2 January 2004
Abstract
Cloning of somatic cells has been investigated actively in cattle, but the cloned calves have been characterized by high birth weight and low survival rate. The present study was conducted to investigate the relationships between survival rate and birth weight in cloned and AI calves. The ear skin fibroblasts were obtained from 2- to 3-year-old Korean native cows (Hanwoo) and the cells were cultured in Dulbeccos Modified Eagles medium (DMEM) supplemented with 10% fetal bovine serum (FBS) at 38.5°C, 5% CO2 in air. Bovine oocytes collected from ovaries obtained from a nearby slaughterhouse were cultured in vitro and then enucleated, injected with donor cells and fused, and cultured to produce cloned embryos at the blastocyst stage. Somatic cell cloning and in vitro culture of embryos were performed by the procedures described previously (Im et al., 2001 AJAS 14, 759–764, and Im et al., 2001 AJAS 14, 1260–1266). A total of 580 cloned embryos at blastocyst stage were transferred to 293 recipient cows; 32 female calves (5.5%) were born (2 of them were born dead). Thirty-four (15 female and 19 male ) calves (57.6%) were born from 59 artificially inseminated Korean native cows as control. Fifteen of the 32 cloned calves were delivered by caesarean section. However, all the artificially inseminated cows delivered naturally. Birth weights of 30 live cloned calves averaged 31.08 kg (>15 kg: 3, 20 kg: 2, 25 kg: 2, 30 kg: 5, 35 kg: 9, 40 kg: 6, <45 kg: 3), while those of female AI calves averaged 23.67 kg (>15 kg: 0, 20 kg: 3, 25 kg: 6, 30 kg: 6, 35 kg: 0, 40 kg: 0, <45 kg: 0). After calving, 11 of 30 cloned calves survived for more than 365 days (birth weight of these calves averaged 28.25 kg), but 19 of 30 calves died within 175 days and their average birth weight was 32.80 kg (650 kg). Gestation length of cows that received cloned embryos was 287 (279–295) days on average (excluding the data of calves delivered by caesarean section) and that of cows artificially inseminated was 287 (255–293) days. In conclusion, the birth weight was significantly correlated (P < 0.05) with survival rate of cloned calves, and survival rates of calves with extremely high or low birth weights were significantly low. However, there was no relationship between gestation length and survival rate.
