Breeding myths...

[AndyPandy]

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I know nothing about equine breeding, but a bit about biology - are horses not subject to the same age-related genetic problems humans are? Thinking of such things as the increased risk of Down's Syndrome as women get pregnant later in life etc?

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The most recent research has shown that Downs syndrome is due to a random event during the formation of sex cells or pregnancy.
So, either, a dodgy egg is released, or something happens in the oviduct on fertilisation.

My theory of Downs syndrome is as follows:
Women are also born with all the eggs they will ever have. Now say, just for the sake of argument, they have 480 eggs. Only one of those 480 eggs is capable of producing a Downs syndrome child. So, the chance of that Downs egg getting randomly ovulated during the first 20 years (after puberty) are fairly small, but as they woman ages, the chance of this egg being ovulated get higher, and higher, and after 40 years (if you're a super-menopause-avoiding-woman ) then, the only egg left will be that Downs egg. So the probability there is 100% of getting a Downs syndrome baby.

These eggs are not damaged by age, they have always been damaged, and were made that way while that woman was still in her mother's uterus!

So, even that case does not say anything about "old eggs", just about the chance of a dodgy egg being ovulated as you get older.

Does that sound about right?

[SpottedCat]

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I know nothing about equine breeding, but a bit about biology - are horses not subject to the same age-related genetic problems humans are? Thinking of such things as the increased risk of Down's Syndrome as women get pregnant later in life etc?

[/ QUOTE ]

The most recent research has shown that Downs syndrome is due to a random event during the formation of sex cells or pregnancy.
So, either, a dodgy egg is released, or something happens in the oviduct on fertilisation.

My theory of Downs syndrome is as follows:
Women are also born with all the eggs they will ever have. Now say, just for the sake of argument, they have 480 eggs. Only one of those 480 eggs is capable of producing a Downs syndrome child. So, the chance of that Downs egg getting randomly ovulated during the first 20 years (after puberty) are fairly small, but as they woman ages, the chance of this egg being ovulated get higher, and higher, and after 40 years (if you're a super-menopause-avoiding-woman ) then, the only egg left will be that Downs egg. So the probability there is 100% of getting a Downs syndrome baby.

These eggs are not damaged by age, they have always been damaged, and were made that way while that woman was still in her mother's uterus!

So, even that case does not say anything about "old eggs", just about the chance of a dodgy egg being ovulated as you get older.

Does that sound about right?

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Ok, I hadn't seen any latest research as I have very little to do with 'pure' biology these days (but if you need any bats counted, badgers spotted or reptiles moved, I'm your girl )

That does make sense from a statistical point of view, and also makes more sense from a biological point of view as (as you previously stated) the oocytes don't go through the same sort of cellular regeneration as other cells (if I remember correctly from that bit of uni!).

So theoretically the same could be true for equines - it's a myth that 'old eggs' cause a problem, but a fact that the older the mare, the more likely that an egg will be released which has a problem, assuming it has not been released earlier in life. Because it is less common for a mare (or human) to have their first offspring at an older age, the prevelance of so called 'age-related' issues is higher than in younger mares/humans, who are more likely to have been retired from breeding once the required number of offspring (more human than horse!!) has been achieved. I think I know what I am trying to say....

[springfallstud]

Very good post AP

Where can you get chlorohexidine solution from? Vet/Chemist?

Will def try the wormer

As we are asking some questions here can i ask where would you recommend buying some colostrum in from for just incase, i've seen some on Ebay!!!!! what are your views on giving this to new foals http://www.petmeds.co.uk/p-3366-foal...colostrum.aspx

[AndyPandy]

Not sure about that particular product, but I've heard relatively good things about:

http://www.farmrite.co.uk/product.ds2?p=106083

And "Hibitane" is the ideal product, although some versions are concentrated so you may have to dilute it to 0.5% CHX.

http://www.medisave.co.uk/hibitane-c...le-p-1859.html

Good luck - let us know how the ivermectin works out

[christine48]

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Hi AP, i wonder if you could help me with a possible myth as you are the breeding guru, ET foals are not as good quality as foals that were born by their natural mother? I have seen a conversation on another forum and was hoping this wasn't true as i plan to do it possibly in a few years with my mare!

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I wonder about this question as my foals all have behavioural traits like their dam. If they were ET foals would they have the behavioural traits of the recipient mare?

[christine48]

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Hi AP, i wonder if you could help me with a possible myth as you are the breeding guru, ET foals are not as good quality as foals that were born by their natural mother? I have seen a conversation on another forum and was hoping this wasn't true as i plan to do it possibly in a few years with my mare!

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I wonder about this question as my foals all have behavioural traits like their dam. If they were ET foals would they have the behavioural traits of the recipient mare?

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Sorry just looked back and noticed Andy Pandy has already answered this one

[nikkiportia]

I've been led to believe that although the eggs of an older mare may be perfectly viable, it's the uterus that causes poor foals in older mares. If I remember rightly the placenta doesn't receive as much blood supply due to cysts and breaking down with age of the uterus wall. Is this correct?

[henryhorn]

Yay! A good and informative post which all of us can learn from.
I don't profess to be an expert and am always happy for posts like this to be put up, last year taught me a lot with losing one foal and almost another to that ecoli bug, and I had no idea that a test was available which might have helped us avoid it.
I think there is room for all of us on here, the professionals who do a marvellous job, the people like us who enjoy breeding but don't devote their lives to it, and the amateur who wants to reproduce their own stock having been thrilled with their mare and want another.
Years ago you just took your mare to the stud, they tried her until they felt she was ready and covered her, waited until a season had been missed and collected her hopefully in foal. there were no tests to prove it, no AI, no scanning etc and twins were a common problem.
We can now scan to see what the situation is with the reprocutive cycle, adjust it if necessary, scan again to see exactly when to cover, and do the deed knowing you couldn't have planned it better! We have scanned again to check the results and tweaked a twin on occasions too. (our vet not us)
So a lot more help is available and with the expertise available with AI the majority of mares can be successfully bred from.
I think there is room for a middle ground so it doesn't have to be quite so technical (obviously with expensive stock managing it as above has to be done) , we cover according to the stallion's signal's and only resort to help if the mare doesn't catch first go. It's reassurring to know we can have help though, and it is a massive benefit to owners because your mare can be there, covered, scanned and home again saving keep fees.
Please keep posting info A-P, I for one would welcome some more info about testing the mare /foal after foaling, I read a little about it but not enough.
We are having a quiet foaling year this time but will be covering our usual mares again this time, hopefully we can get slightly earlier dates, though the weather here means no way can you foal outside prior to early May..

[AndyPandy]

I think it's probably delayed uterine clearance, reduced uterine tone, reduced immune response, possible interference from cysts, poorer blood supply, poorer cervical integrity, possible fibrosis from infections and a number of other age-associated problems

But yes, older mares can be problematic, but not because of their "old eggs"!

[KarynK]

I had the privilege many years ago to have Twink Allen teach me on a breeding course at the National Stud.

He came and collected us and took us on a tour of the Fertility Unit. Those of that have met him will know his sense of humour! He had a game with us on What’s That! One of the What’s that’s was a 13.2 hh small fine stallion, I guessed show pony, but it was a TB.

His mother had received damage due to a prior foaling and had become infertile. Twink got her in foal but the result was tiny due to lack of sufficient nutrition during the pregnancy, a result of the damage> But as he demonstrated to us, he had us collecting!!! He was ideal to collect semen from easy to handle and threw full sized foals!!!