290 THE FACTORS ON RATES OF ABNORMALITY, DISEASE AND MORTALITY OF CALVES DERIVED FROM IN VITRO EMBRYOS OF KOREAN NATIVE CATTLE

Abstract

In Korea, in vitro production and transfer of bovine embryos has advanced remarkably and applied commercially. However, in vitro-produced embryos result in lower pregnancy and higher abortion rates and in some cases increased rates of abnormality and mortality in calves. The present study was conducted to investigate the effects of various factors such as recipient parity, delivery season, offspring number, pregnancy period, delivery type, midwifery type, dystocia and vaccination, on the viability of calves derived from embryos produced in vitro. Korean Native Cow ovaries were obtained from local slaughterhouse and cumulus-oocyte complexes (COCs) were aspirated from 2 to 8 mm follicles. Selected COCs were matured in TCM-199 supplemented with 10% fetal calf serum (FBS), 1 ¼ML FSH, 10 ¼ML LH and 1 ¼ML Estradiol-17² for 20-22 h. In vitro-matured oocytes were fertilized using frozen-thawed percoll separated semen (Day 0) in fer-TALP medium for 20 h. The presumptive zygotes were cultured in CR1aa medium supplemented with 0.3% BSA (before Day 3) or 10%FBS (After Day 3). All types of cultures were made in an incubator at 38.5°, 5% CO₂ in air. Statistical analysis was performed using the Chi-square test. Two blastocysts were transferred to the Holstein recipients (n = 1888). The parturition was occurred in total 755 recipients. There was no difference in the abnormality of calves among treatments. The incidence of disease was significantly higher in single calf than twin calves (18.4 vs. 6.7%), in multiparous than nulliparous group (40.0 vs. 9.9%), in eutocia than dystocia group (20.0 vs. 4.8%), in spring and winter groups than summer and autumn groups (20.3, 22.7 vs. 4.3, 0.0%), and in non-vaccinated than vaccinated group (22.7 vs. 1.6%), respectively (p < 0.05). The rate of mortality was significantly higher when transferred into nulliparous than multiparous (22.3 vs. 0.0%), when were dystocia than eutocia group (71.4 vs. 14.1%), when were non-midwifery than midwifery (45.0 vs. 13.6), when delayed midwifery than earlier midwifery (31.6 vs. 11.5%), and when were non-vaccinated than vaccinated group (28.0 vs. 9.8%), respectively (P < 0.05). The present study suggested that the viability of bovine calves derived from in vitro was affected by the recipient parity, parturition treatment technique and vaccination.

This study was supported by the BIO-GREEN 21 PROGRAM.