Effects of stage and quality of embryo, synchrony between donor and recipient and difficulty of transfer on pregnancy rate following non-surgical transfer of frozen-thawed bovine embryos

Lee, Eun-song; Jo, Choong-ho; Hwang, Woo-suk

Korean Journal of Veterinary Research 1989;29(3):361-371.

Eun-song Lee, Choong-ho Jo, Woo-suk Hwang

College of Veterinary Medicine, Seoul National University

젖소 동결수정란의 비외과적 이식에 있어서 수정란의 상태 및 이시조건이 수태율에 미치는 영향

이은송, 조충호, 황우석

서울대학교 수의과대학

Abstract

This study was performed to investigate the effects of stage and quality of embryo, synchrony between donor and recipient and difficulty of transfer on pregnancy rate following non-surgical transfer of frozen-thawed bovine embryos. The results were as follows; 1. The overall pregnancy rate of this experiment was 63.4% and that of heifers(73.1%) was higher than that of cows(46.7%). 2. The pregnancy rates of recipients transferred with morulae, early blastocysts and blastocysts were 50.0%, 64.7% and 71. 4%, respectively. 3. The pregnancy rate of recipients transferred with good embryos(67.9%) was higher than that of recipients transferred with fair embryos(53.8%). 4. The pregnancy rates of embryos transferred to left and right uterine horn were 63.2% and 63.6%, respectively. 5. The pregnancy rate of recipients in estrous synchrony 0(76.2%) was higher than those of recipients in synchrony -1(55.6%) and +1(44.4%). 6. The pregnancy rate of recipients transferred with 2 embryos (71. 4%) was higher than that of recipients transferred with 1 embryo(61.8%). 7. The pregnancy rate of embryos transferred to uterine tip (72.0%) was higher than that of embryos transferred to uterine base(50.0%). 8. Ease of transfer was ranked to a scale of one to three on the basis of increasing difficulty. Transfers ranked as ease score 1 accounted for 77.8% of pregnancies and had higher pregnancy rate than ease score 2(66.7%) or 3(45.5%). 9. The pregnancy rate of recipients with excellent corpus luteum(CL) (70.0%) was higher than those of recipients with good CL(61.1%) or fair CL(61.5) %. In reviewing above results, it was considered that the factors such as embryo stage, embryo quality, estrous synchrony, corpus luteum quality, transfer site within uterus, recipient's parity and ease score affected the pregnancy rate after non-surgical transfer of frozen-thawed bovine embryos.

Key Words: embryo transfer, frozen embryo, cattle, pregnancy rate, recipient