소의 발정동기화 및 동결수정란 이식에 관한 연구 = A Study on the Synchronization of Estrus and the Frozen Embryo Transfer in Cattle

다국어 초록 (Multilingual Abstract)

This study was conducted to investigate the effects of breed and parity of recipients, grade of frozen-thawed embryos and degree of donor-recipients synchrony on conception rate when the frozen-thawed bovine embryos were transferred to 60 heads of Korean Native cattle (KNC), Holstein and crossbred in Livestock Experiment Station, Rural Development Administration, and nearby large farms. To synchronize the estrus, regularly cycling heifers and cows of 114 heads were injected with 50㎍ of cloprosternol twice 11 days apart. The results obtained from this study were summarized as follows; 1. Cows showed estrus with the range of 2-6 days after the first shot and 2.5-4 days after the second shot. The rate of response was higher in the second shot (82.5%) than the first shot (67.5%). 2. The rate of response to cloprostenol after the first shot was high in crossbred, Holstein and KNC in the order, although no significant differences were noted in the second shot. 3. The overall conception rate was 45.0% and that of Holstein was 52.2% (24/46) and that of KNC was 37.5% (3/8). However none of crossbred was pregnant. 4. The conception rate of heifers (46.9%) was slightly higher than that (42.9%) of cows. 5. The conception rate of cattle transferred with excellent, good and fair embryos were 68.9%, 35.9% and 40.9%, respectively. 6. The conception rate was highest when the recipients began to show estrus 12 hours later than donor did.