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Large offspring syndrome in cattle and sheep
L E Young1, K D Sinclair, I Wilmut
1Roslin Institute (Edinburgh), Midlothian, UK.
Reviews of Reproduction
|November 26, 1998
Summary
Exposure to unusual environments before the blastocyst stage can cause large offspring syndrome in bovine and ovine species. This condition leads to organ defects and reproductive complications, limiting the use of embryo production technologies.
Area of Science:
- Reproductive biology
- Developmental biology
- Animal science
Background:
- In vitro embryo production is widely used in humans and other species.
- Large offspring syndrome (LOS) in bovine and ovine species presents challenges.
- LOS is characterized by abnormally large offspring with organ defects.
Purpose of the Study:
- To identify environmental factors causing large offspring syndrome in bovine and ovine embryos.
- To understand the mechanisms underlying early embryonic perturbation leading to LOS.
- To address limitations in large-scale application of embryo production technologies.
Main Methods:
- Exposure of bovine and ovine embryos to various pre-blastocyst environments.
- Identification of four specific situations inducing the syndrome: in vitro culture, asynchronous embryo transfer, nuclear transfer, and high urea diets.
- Observation of offspring for size abnormalities and organ defects.
Main Results:
- Unusually large offspring with organ defects were observed following specific environmental exposures.
- Difficult parturition and increased fetal/neonatal losses were noted in affected animals.
- The syndrome's occurrence and manifestation of symptoms were unpredictable across situations.
Conclusions:
- Environmental factors prior to the blastocyst stage can induce large offspring syndrome.
- The precise environmental triggers and underlying mechanisms of LOS remain unidentified.
- Further research is needed to overcome challenges associated with embryo production technologies.