Recycling bovine embryos for nuclear transfer.

Area of Science:

• Reproductive biology
• Developmental biology
• Animal science

Background:

• Nuclear transfer (NT) involves using donor nuclei from somatic cells or embryos for cloning.
• Serial transfer, or NT recycling, reuses cells from NT embryos for subsequent NT rounds.
• This technique aims to improve nuclear reprogramming and increase the number of cloned offspring.

Purpose of the Study:

• To evaluate the embryonic developmental competence of bovine embryos produced through multiple rounds of NT recycling.
• To assess the reproductive outcomes and fetal development in subsequent generations of cloned cattle.
• To investigate the impact of a novel vitrification method on the efficiency of NT recycling.

Main Methods:

• Nuclear transfer was performed on bovine embryos across multiple generations (recycling).
• Embryonic developmental competence was assessed.
• Pregnancy rates and fetal survival were monitored in recipient animals.
• A novel vitrification technique was applied to NT embryos.

Main Results:

• Embryonic developmental competence did not differ significantly between clones from three generations of bovine embryo recycling.
• One live offspring was obtained from the second generation, and pregnancies from the third generation were achieved.
• Lower pregnancy rates and higher fetal losses were observed in later generations compared to the first generation.
• The novel vitrification method addressed practical limitations associated with NT recycling.

Conclusions:

• Bovine embryo recycling maintains embryonic developmental competence across generations.
• While feasible, serial NT rounds lead to reduced reproductive efficiency and increased fetal loss.
• Vitrification offers a promising solution to overcome practical challenges in NT recycling technology.