| Bossanova |
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| 23/02/2008 11:58 |
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Re: Breeding myths...
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Quote:
Old mares have old, damaged eggs, and will produce foals with problems such as bad legs, deformities etc.
Eggs produced by a 20 year old mare, are themselves 20 years old, as each mare is born with a all the eggs they will ever have. These older eggs may not be as viable, and so may be less likely to produce pregnancies. However, DNA is DNA, and the genes in each egg remain unchanged, whatever the age of the mare (and the egg). Environmental factors and mare/stallion genetics cause these problems, not old eggs!
I only disagree with this one. DNA suffers damage as time goes on. As egg cells are essentially the same as normal body cells bar the number of chromosomes, their DNA can also be damaged. As the mare gets older the repair mechanism cannot always repair DNA damage sufficiently so mutations can occur.
Also, as DNA goes through the cycle of damage-repair-damage-reapir, it shortens and if shortended to a significant level, genetic material is lost.