choosing the sex of your foal

appyjude

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AP,

I could phone you to ask this, but figured that I may as well put it to the board also. I have read in some of my American magazines about the ability to "chose the sex of your foal" when doing AI - i)at what stage is it done i.e. is it get 'em pregnant, test then pinch if not what you want? ii) How often is it done - it sounds reasonably new iii)cost and implications - will we see a dramatic decrease in geldings due to demand for fillies?

Question is based on very limited amount of straws being available from a stallion who has now been gelded and mare that was pregnant to him aborted last year.

Great pic of lavender btw.

Jude. x
 

S_N

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Foetal sexing is generally done at 60/70 days post last covering date. And is not 100% accurate - we've already had 2 wrong this year! Unless the mare was covered and in foal on a Feb cover, then pinching it out at 60/70 days, would not leave a very big window for re-covering - that is if you can get the mare to cycle properly again that season. Often mares that are scanned + at 28 days and then are scanend - at 42, are very difficult to encourage to start cycling again - highlighted for me in Kentucky in 2001, at the beginning of MRLS (Mare Reproductive Loss Syndrome).
 

UCD2007

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Stallion sperm can be sex sorted prior to insemination, however it is very costly and as far as I know you need reasonable large numbers of live sperm to start and only end up with very few living sperm in the end, so not the kind of thing that would work very well if you only have a few straws of frozen semen.

Sex pre-selection is based on identifying differences between X- and Y-bearing sperm. The X chromosome contains about 4% more DNA in cattle and horses than the Y chromosome. Therefore, this difference in DNA content can be used to distinguish and select X from Y bearing sperm. The DNA is labelled and run through a machine (flow cytometer) that is able to sort the sperm based on the DNA content.

The website for the company in Colorado, USA that offers this service is:
http://www.xyinc.com/index.php
 

GreedyGuts

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This is acheived by sorting the sperm prior to insemination. This is done using a technique called flow cytometry. The DNA within the sperm cells is stained with a fluorescent dye. The female cells contain about 4% more DNA than the male cells (the X chromosome is bigger than the Y) and so they glow brighter. The cells are then charged on the basis of how brightly they glow and seperated using this charge. (Hope that makes sense!) This technique sorts sperm with about 90% accuracy.

Sex sorted cattle semen has been commercially available for a while but the technique is still in it's infancy in horses; it requires the use of small insemination doses, and some studies have suggested that the conception rate to sexed semen is less than that to unsorted sperm. The technique has been patented by the US company that developed it and requires funky equipment, so not cheap or widely available.

In reality it is unlikely to be available for a while yet, and even then the risks and costs will limit its use as a technique. I can't see that this will have any bearing on the gender distribution of foals for many years if ever.

Sorting must be done when the semen is fresh, so it wouldn't be of much use to you even if it was widely available. As SNight said sexing and pinching is a bit of a nonstarter because it's not super accurate, and abortion at that stage of pregnancy tends to leave mares in a reproductive limbo. Not much to do but cross your fingers for a filly really, which can be very frustrating I know!
 

AndyPandy

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Right then... well:

We've had a good few descriptions of flow cytometry. Yes, it is the only proven method of sorting sperm on a sex-selection basis. Pregnancy rates using this method are very low (37.5% for fresh, 13% for frozen), plus it's very expensive. It's not a viable option for most people.

Another method which has been proposed for sex selection is this: X-chromosome bearing sperm (female) are heavier, and slower swimming than Y-chromosome bearing sperm (male), because the X-chromosome is large in comparison to the Y chromosome, and when you're the smallest cell in the body, that weight difference can make a difference to speed. Theoretically, if the mare is bred close to ovulation, there should be a higher incidence of colts born. Conversely, because the Y-sperm are fast, but short-lived, breeding further from ovulation would give rise to a higher incidence of fillies. It sounds nice, but there is conflicting information from a number of researchers. Plus, breeding further from ovulation in equines would lead to a lower conception rate.

Finally, there is another option, which is not yet commercially available in equines, but is available to some cattle breeders in the States. The theory is that X-bearing and Y-bearing sperm have different "properties". Those properties could be metabolism-related, antigens on the head, or something else (the manufacturers have not disclosed precisely what the difference is!). Anyway, there have been solutions developed which "kill" "half" of any sperm exposed to it (one which kills female sperm, one which kills male sperm). Inital work has shown that the sperm are separated and/or half (roughly) of the sperm in a sample die. Now, I have no idea if this actually works, but I have seen claims of people using the solutions saying "it's now possible to choose the sex of your foal". It's a very interesting premise.

I'm investigating this last product and its claims. As soon as I have more information, I will let you all know!

Hope that helps.
 

AndyPandy

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Oh, and I've just seen that someone else is offering a "special washout" for the mare, 35 minutes before covering to choose the sex of your foal! Who knows if it works. At the moment, you're probably best of just hoping for the one you want!
 

KarynK

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Was offered it here in the UK last year but only on chilled and fresh and I was using frozen so I didn't enquire further into techniques, fertility rates etc.
 

AndyPandy

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It sounds very interesting, but I can't see how it would work. Also, if it was that successful, then I don't understand why it wouldn't have already gained more interest. Too good to be true? Probably!
smile.gif
 

AJBliss

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I imagine that as bulls are heavily selected for fertility, their semen would be more resilient to the sort of handling required at this point for sex-selection... I can't see this being terribly cost effective in the horse industry where there is not nearly such a critical demand for one sex or the other, as in cattle. Colts have a much brighter future (as geldings or stallions) than do 99.9% of dairy bull calves--at least in the States! When I worked on a uni dairy in the US ten years ago, there were adverts everywhere in the periodicals for sex-selected semen--and not as new technology, but it still hasn't translated to our equine world much beyond "novelty" from what I can tell.
 

Eceni

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[ QUOTE ]
Oh, and I've just seen that someone else is offering a "special washout" for the mare, 35 minutes before covering to choose the sex of your foal! Who knows if it works. At the moment, you're probably best of just hoping for the one you want!

[/ QUOTE ]

Which is based on pH effect, and is similar to various theories about women eating certain things (can't remember what) for the meal before coitus in order to shift the odds in favour of a particular sex of child. I only know this because my mother said she'd done it to ensure I was female... And got up and walked around for an hour or two afterwards so all the short-lived little male sperm had swum themselves to death going uphill, then she could like down and let the female sperm do their thing....

not sure if that's viable (not sure I want to know, actually) but changing the pH of the urine and thereby vaginal environment might make a difference, so washing out would be an extension of that.

E
 

Faithkat

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[ QUOTE ]
At the moment, you're probably best of just hoping for the one you want!

[/ QUOTE ]

I spent 11 months poking my mare in the side and saying "you'd better have a chestnut filly in there" (and this was after she'd had a twin embryo crushed!) . . . and guess what . . . . she had a chestnut filly!!!! Sadly, though, she's now going grey
frown.gif
 

JanetGeorge

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As a breeder of pure Irish Draughts, I WANT fillies! My mares don't care - this year I got 4 colts and 1 filly! But I'm not sure if I would want to go down the road of selecting for sex. Certainly in the case of one mare (who has given me 4 fillies and a colt) if I HADN'T got that colt I would have really missed out, as he is stunning and a FAR 'better' example of the breed than her fillies.

Part of the fun of breeding is hoping for a colt/filly - and seeing what you've got! Even if it's 'wrong', as long as it's healthy and the mare is fine, I don't really mind too much!
 

KarynK

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[ QUOTE ]
It sounds very interesting, but I can't see how it would work. Also, if it was that successful, then I don't understand why it wouldn't have already gained more interest. Too good to be true? Probably!
smile.gif


[/ QUOTE ]

Just heard some gosip that the person supposedly able to do this is not proving to be very trustworthy!!!! So probably for the best I didn't play! I'll sit this out for a while me thinks!!
 
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