Effect of laparoscopic ovum pick-up on ovine in vitro oocyte maturation and somatic cell nuclear transfer embryo...

Mammalian somatic cell nuclear transfer (SCNT) is widely used in agricultural research and biomedicine, but remains inefficient and requires large number of oocytes, typically obtained from slaughterhouses (SH) or cull animals with or without superstimulation (Culls-FSH and Culls). Laparoscopic ovum pick-up (LOPU) is a less invasive method to collect oocytes and improves SCNT embryo development. Yet no study has directly compared all four sources of oocytes on SCNT embryo development in sheep. This study evaluated the effect of oocyte source on in vitro maturation (IVM) and SCNT embryo in vitro and in vivo development. IVM rates were significantly higher in LOPU-derived oocytes than SH oocytes both in the breeding season (93.6% vs 71.9%, P=0.0007) and non-breeding season (91.1% vs 66.5%, P=0.0013). In the breeding season, the LOPU group produced a higher SCNT blastocyst rate than the SH group (41.7% vs 11.8%, P=0.045), whereas no difference was observed in the non-breeding season. Because higher blastocyst development was expected, fewer one-cell embryos were transferred per recipient for the LOPU group compared with SH, Culls-FSH, and Culls (4.4 vs. 15.8, 14.5, and 18.5, P < 0.001). Neither the initial pregnancy rates nor the full-term rates differed among groups. But LOPU group showed a significantly greater SCNT efficiency than the SH and two Culls groups (14.0% vs 1.94%, 1.21%, and 1.97%, P < 0.001). In conclusion, LOPU produced the highest-quality oocytes among the four oocyte sources, resulting in greater oocyte maturation and more developmentally competent embryos both in vitro and in vivo, despite limited number of embryo transfers (n = 5).