Non-Surgical Transfer of Fresh or Frozen-Thawed Ovine Embryos by Laparoscopy

Abstract

The present study was conducted to examine survival of fresh and frozen-thawed ovine embryos after embryo transfer (ET) using laparoscopy or in vitro culture. Embryos were collected on Day 7.5 (Day 0 =sponge removal) from donor ewes superovulated by pre-treatment of progestogen-impregnated intravaginal sponges (FGA) for 12 days and a single injection of follicle stimulating hormone (FSH) and equine chorionic gonadotrophin (eCG), at 2 days and 1 day before sponge removal. The donor ewes showed estrus between 12 h and 30 h (the mean time: 15.6 h) after sponge removal. Embryo transfer of fresh or frozen-thawed embryos was carried out on Day 7.5 in 37 recipient ewes using laparoscopic technique. Frozen-thawed morulae or blastocysts were cultured to examine their viability in a modified synthetic oviduct fluid medium (SOFM) for 24 h. The lambing rates after ET with fresh and frozen-thawed embryos were 33.3% (6/18) and 26.3% (5/19), respectively. The developmental stage (morula or blastocyst) affected the survival rate of frozen-thawed embryos transferred (54.5% and 0%, respectively). The survival rate (development to blastocyst or hatched blastocyst) of frozen-thawed embryos after 24 h in culture was 40.9% (9/22). The present results indicate that ovine ET using laparoscopy is a useful technique. But, the lambing and survival rates of both fresh and frozen-thawed embryos were low, and remained to be improved.