Should fertility be a necessity for stallion grading?

[AndyPandy]

In horse breeding, it is my opinion that the genetic factors which negatively impact fertility of stallions are ignored, as horses are often bred purely on the basis of athletic performance, pedigree, conformation and sometimes trainability. Reproductive potential is not used as a screening trait as it is in cattle, sheep, pigs etc.

I believe that this is gradually leading to a greater number of stallions (and mares, in fact) being bred which have fertility problems. It is my belief that good fertility should be an essential trait in graded stallions - after all - what is the point in a stallion being graded if it is unable to produce offspring, or passes on an undesirable trait like infertility to its progeny?

As far as I am aware, some of the studbooks in the rest of Europe do screen stallions put forward for grading for infertility... when will British studbooks do the same?

Jamie

 

[severnmiles]

How many horses are bred purely to breed from? If you breed 5 foals from a stallion with fertility problems say two are fillies and three colts, out of that number I doubt any one of the colts would be stallion potential therefore they get gelded. Fillies go off into sport and you have a 50/50 chance of being able to breed from them...

I don't think a stallion that could produce a Grade A SJ'er or an Advanced eventer should be denied the right due to fertility problems...are all fertility problems hereditory?

 

[AndyPandy]

Unless there is some phyical injury, disease etc. which directly affects the testes, then any infertility must either have been passed on from the dam and/or sire, or be due to a random genetic mutation of the dam's egg or sire's sperm which then becomes hereditory in the next generation... so for the mostpart, infertility is genetic and heritable.

I don't think that infertility alone should be enough to prevent a stallion from being graded, but I do think it needs to be monitored. My concern is that there may be a cumulative effect of infertility in certain bloodlines/pedigrees - so that you get a way down the line, produce a fantastic competition stallion which is then effectively unable to produce further offspring.

Infertility has been ignored in humans for many years, and is now treated with ever advancing medical procedures (IVF, ICSI etc.) but because we are now treating these infertile men, the infertility levels are increasing, and some couples infertility is now so bad that medical technology has fallen behind. We are still a way off reproducable commercial IVF in horses, so I think something needs to be done before the problem gets worse.

 

[Panther]

Andypandy you are so right.. and grading I believe is very very poor!!
Practically inferitile and most often lame get graded on their 'good' days... doesn't bode well does it..

 

[magic104]

Fertility is something to consider & should be made known to the mare owners, after all it is them footing the vet bills for scans etc & the livery costs. I have heard rumours about Lord David S & his fertility so makes you wonder when they blame the mare if this is always the case. It would not be in the stallion's owner's interest for it to get out that the fertility is low, but it would save an awful lot of money & time. I am not sure if it should affect the grading of the horse, but it should most defiantly be noted.

 

[airedale]

Even if the fertility isn't tested at the grading (and tbh I'd like to see 'may be subjected to blood testing' at all gradings - i.e. random 'dope testing' ) I very strongly feel as a mare owner that all graded stallions and the grading society that issues the covering certs should issue the fertility statistics for each stallion at the end of the covering season

i.e. stallion X mares covered y % in foal Z

plus stats for Natural cover, Chilled AI and Frozen AI as available from that stallion.

I used a stallion and very fertile mare didn't take (she'd taken first time twice before and has again this year)

turned out the stallion was fertile by natural cover and was supposedly fertile by AI but the 'chilled semen AI fertility' was only as it turned out - valid for AI done when the mare was at their stud - the semen didn't travel and the motility chilled and travelled down from Northumberland to Surrey - TWICE - was 28% and 22%

mare took first time at her next season to a different stallion with an 80%+ (can't remember) motility by chilled AI

and all done by the same vets in all cases with the mare at home.

and as you said above - the stud blamed the mare and despite my representations and those of my vet we didn't get the stud fee back and Trading STandards did nothing much of any use to help either.

 

[ColouredFan]

Airedale the situation you have described above is the reason why i think mare owners should be given fertility information. I bet if a stallion was shown to have a low fertility people would think twice before using them, again for the very reason you mentioned - loosing potentially alot of money.

 

[Fahrenheit]

I agree with airedale. When we first started to ship chilled semen out, my stallion had a test collection that was chilled and left and look at after 24 and 48 hours to see what the semen quality was like and even now we usually keep back some of the semen to see what its like the next day, just to keep an eye on what its upto.

I think people should be more aware of the quality of the stallions semen they are using but as always there are going to be stallions that defy the rules, I knew a stallion that had very low quality semen that didn't chill and didn't freeze but by fresh and natural he had higher than average pregnancy rates, hence he was only available by natural and fresh AI.

I do the stats for all my stallions at the end of the season, though this season isn't going to look too good as I am not doing very many mares as I haven't been well. The only problem I see with stats is people will be put off taking in known differcult breeders and will stick with mares under a certain age with no known breeding problems in the past, because they wouldn't want a differcult breeder to affect their stats and I think that would be ashame.

 

[airedale]

However - as with a previous discussion - mares with fertility problems - a lot of these can be passed on to their progeny - so perhaps if they aren't bred from this would be a good thing ? - e.g. TB (and other) mares with a bad vulva conformation

 

[Fahrenheit]

I agree badly conformed horses shouldn't be bred from but there are mares with breeding differculties that are caused by other problems like my mare who just had a foal after quite a few years of trying, what originally caused her problem was nothing to do with her breeding conformation, she has excellent breeding conformation, excellent conformation, excellent breeding, excellent competition records.
One of my older broodmares required castlicks for the past two foals but after at least 10 foals (that I know of!) i think that thats perfectly acceptable, she isn't as elastic has she once was in that area! I fully agree with having stats for the stallions, all i'm saying is that it would be ashame if places that have specialised in taking differcult mares (with genuine problems) suddenly stopped taking them just to keep their stats up.

 

[magic104]

So does that mean you would not have perserved with a mare like Betty Bug? What about a mare that had had foals but in later life proves a bit more difficult? I will stick by my view that mare owners should know the fertility rate of the stallion they wish to use & this information should be readily available.

 

[Damien]

indeed some EU studbooks do screen for fertility but it is very debatable amongst stallion owners on the continent that is it a valid examination.

A young stallions' semen, examined in the month of February for example will not necessarily produce conclusive results. The same stallion could be examined at the age of five at the height of the breeding season and show a very satisfactory result.

A stallion could be examined having had a high temeperature at some point and show very poor motility, or a stallion in high level competition exposed to stress and physical exersion may also interfere with the results.

No one truly knows what makes a stallion fertile or not, whilst we can examine motility under a microscope and use the most modern of techniques to freeze, extend etc what actually gives a stallion high fertility remains unkown.

We see semen with high progressive motility and low progressive motility from a variety of stallions every year. We are often disapointed when everything is text book with semen looking fanatstic but the mare does not become pregnant, then on occasion it's the other way around with low progressive motility at a mere 22% and insemination post ovulation and the mare is pregnant! Mother nature still holds her secrets.

Mares have their own problems too, heamoragic follicles, fluid issues, restrictive passageways poor uetrine tension, etc etc etc.......

With artifical insemination and semen distribution, statistics become even more variable: some vets have little experience with equine reproduction, some stallions don't react well to certain extenders, some mares are infertile and thus the measurable factors become even more unreliable.

So yes whilst I agree that screening a stallion to verify that the stallion is fertile should be performed, I do not feel that it is conclusive as to whether or not he will be able to produce a high number of pregnancies and should not decide whether a stallion is worthy of a breeding license or not.

If stud books are to publish data then they need to have all the data regarding the breeding and I doubt you will ever get a vet sign on the dotted line that he has only ever inseminated cows! LOL

 

[Fahrenheit]

I think you have made some very good points, for true fertility to be measured, all factors are going to have to be taken into consideration, ie time of year, work loads, vet history for the stallion and then you are going to have to consider the mares that were being used, their ages, their breeding conformation, their breeding history, what they did on their cycle, their odema scores etc etc I just can't see a true full on survey being possible.
Maybe a snap shot would be better as a guide to mare owners ie for fresh semen only measure pregnancy rates on mares inseminated with fresh between may and july on mares aged between 4 and 12, that odema scores were 2 or under (on the 1 to 3 scale my vet uses - he classed Betty as a 3++ for anyone that was interested in that fact) and that ovulated timely to the insemination, similar could be done for chilled semen and it would be slightly more differcult for natural covering because not everyone scans follicles and ovulations when covering naturally in hand, I do because I only like to cover the mare the one time. That way the stallion owner can say here is my stallions stats on mares covered between may and july, only taking into account mares aged 4 to 12, with odema scores of 2 and under that ovulated timely to insemination. That way mare owners get an idea of the pregnancy rates of the stallion on what we can class as normal as possible inseminations but the stallion owner won't feel that they have to refuse giving a 'problem' mare a go at getting pregnant incase it infects their stallions stats. One of the big AI Centres did something similar with their sussess rates with frozen semen, they took 3 different studs and the mare that would full within certain categories (ie as above) to measure their success rate at inseminating mares with frozen semen compaired to mares with fresh and chilled, it was very interesting I went to their seminar on it.

 

[AndyPandy]

I don't think anyone would suggest that a fertility assessment should be made on the basis of motility, extended chilled lifespan and/or freezability alone! That would be foolish.

However, there are plenty of factors which can now be tested including how intact the genetic material in the sperm is, and the basic characteristics of the sperms ability to penetrate the egg, among other things.

I believe that an extensive assessment of the stallion's semen should be made on several occassions throughout one season, and this data should be used to give an estimate potential for fertility. Obviously a stallion whose semen, on average over three collections, has 95% abnormal morphology with no acrosomes, 5% progressive motility and a chilled lifespan of 2 hours is not likely to be a very productive sire.

However, whatever happens, this data can be used in a positive way. Used in conjunction with data of percentage conception for natural & AI, and data for whether or not these pregnancies go to full term; the "fertility" tests can quickly (within 1-2 years) become extremely useful. Infertile stallions can be picked up and then either have their graded status revoked, or be used in ICSI-type programmes if it is thought that they could potentially produce top quality youngstock.

Regular, extensive testing of fertility and good record keeping may also elucidate interesting indicators of fertility and/or infertility that we are not yet aware of.

 

[Damien]

[ QUOTE ]
However, there are plenty of factors which can now be tested including how intact the genetic material in the sperm is, and the basic characteristics of the sperms ability to penetrate the egg, among other things.

[/ QUOTE ]

Would like to learn more on the subject AP, where is this being done and how soon do you think it will be made readily availible?

 

[AndyPandy]

Testing which is already available subject to the facilities of the lab where you work are:

Hypo-osmotic swelling test, which is a useful indicator of how well the sperm cells cope with a changing external environment; basically how strong the cells plasma membranes are.

Chromatin can be stained using toluidine blue (TB) and acridine orange (AO) and 1000x light microscopy & 400x fluorescence microscopy, to assess the percentage of sperm with defective genetic packing. There are other stains available.

Commercially available Spermac stain can be used to make assessments of the acrosomes of the sperm cells, and thus their likely ability to be able to penetrate the egg. These can be extended using a ZP-binding assay, but is difficult and expensive, even for research labs!

Other tests, such as metabolic status & mitochondrial activity are available, as well as flow cytometry tests which can measure a wide range of veriables, although I am not sure if they are currently available commercially.

Unfortunately, in this country, as far as I am aware, there are very few labs/studs which can provide an extensive fertility work-up.

 

[Damien]

I understand the labs using Chromatin staining and fluoerescnt microscopes still maintain that even with all the scientific technology made availible to them they are still not in a position to state what makes a stallions semen highly reproductive or not.

...The proof is in the eating of the pudding is basically what I was told...

But from what you are saying there are other lab tests that go beyond this that can? But they are not availible in the UK?

 

[AndyPandy]

Nothing artificial (i.e. any lab test) can yet answer the question "is this stallion fertile?". However, the tests I have mentioned are useful for detecting traits which have been associated with stallions which seem to be "infertile".

The majority of research from the last 3-4 years shows an extremely strong correlation between chromatin integrity and fertility (in quite a few species e.g. Erenpreiss et al., 2006). So, although no lab test will give you a true representation of a stallion's fertility, assessments, including chromatin test WILL give you relevant and possibly useful measures of characteristics related to fertility.