The science of attraction...

[AndyPandy]

Ever wondered why horses choose a particular mate in the wild? Why some mares in season will "show" for some stallions but not others? It's probably down to their immune systems

Burger et al presented a paper at ISER this year: "Studies in mice and humans have demonstrated that mating preferences are influenced by the major histocompatibility complex (MHC). Mice and humans tend to choose a MHC dissimilar companion, which is believed to help avoid inbreeding and increase chances of survival of offspring. In the study, free-roaming mares were placed one at a time in a barn with six stabled stallions. The mare was allowed to choose her preferred stallion, who was then removed from the stable. She was then allowed to choose her preferred stallion out of the remaining stallions, who was then removed, and so forth until only two stallions were left. The mares were tested in estrus and in diestrus (when the mare is not cycling) and with or without their vision blocked. The mares were then compared to the stallions on the basis of MHC. The mares choice varied significantly based on the stage of cycle when tested. During diestrus choice was not related to MHC differences, but during estrus, there was a tendency for mares to pick MHC dissimilar stallions."

This method of choice is most likely the case because it will produce offspring with (essentially) a better immune system, through the combination of genes for very different MHCs.

So, it's probably not that your mare "only likes pretty boys" or "only fancies the really butch ones", but that she's being particular about her partner's immunity

 

[Beatrice5]

Wow that was facinating - thank you. Sadly how many mares get any choice in the matter but hey thats another story . When I take my girls ( Dogs) to stud they get to play with the dog first if they don't like him then we find one they do. As long as he is health tested clear and I am happy with his temprement etc then I let them choose - sadly it isn't as easy with horses I know.

 

[Alexart]

That's really interesting - it works the other way too though - we've noticed given the choice our friesian stallion will go for a TB/ cob whatever else instead of a friesian anytime! We've watched them when he's been turned out with a few mares and even if there is a friesian mare in full season he will pay more attention to a TB that isn't quite in season, and sometimes will even ignore the friesian mares until he has 'got' the TB mare!!! That's why when we cover visiting mares in hand we have to make sure he can't see other mares so he doesn't get distracted when he's supposed to be covering a pure friesian!!!

We've also had arab mares for our then arab stallion - that would get really angry at the arab but try a mad dash towards the big black friesian stallion and act like a total slapper towards him rather than our little arab!!!

I think they've done a similar study in humans and found women were more attracted to men with very different immune systems - quite cool when you think about it - we're not so different from the animals!!!

 

[Flyingbuck]

Had never considered immune systems - very interesting - thanks.

 

[Simsar]

Very interesting thank you AP.

 

[Honey08]

Thanks Andy.

My mare went to stud this year and didn't take. The stud said sometime the mare and stallion are just not compatible, and suggested sending her to another stallion next year instead. I'm not sure, thinking I'd be throwing good money after bad. Anyone any ideas?

 

[AndyPandy]

Thanks Andy.

My mare went to stud this year and didn't take. The stud said sometime the mare and stallion are just not compatible, and suggested sending her to another stallion next year instead. I'm not sure, thinking I'd be throwing good money after bad. Anyone any ideas?

Need more info:

Your mare's age
Your mare's status (maiden, foaling, barren, empty)
Stallion's age
Covering method (single natural, repeated natural, fresh AI etc)
Stallion's fertility (preferably a first cycle pregnancy rate, rather than "good/great/ok"
The stud's competence (good reputation?)
The vet's competence (well known?)

I bet we can find a problem there before going down the road of stallion-mare incompatibility

 

[Flyingbuck]

Need more info:

Your mare's age
Your mare's status (maiden, foaling, barren, empty)
Stallion's age
Covering method (single natural, repeated natural, fresh AI etc)
Stallion's fertility (preferably a first cycle pregnancy rate, rather than "good/great/ok"
The stud's competence (good reputation?)
The vet's competence (well known?)

I bet we can find a problem there before going down the road of stallion-mare incompatibility

Apart from the above AP. do you think the weather could also have played a part? We were lucky enough to get our 5 mares in foal this season, but I know other studs were not so lucky and blamed the weather.

 

[ruby1]

I was thinking along the same lines as Honey08 as our mare was similar this year.

AI'd twice but she did retain fluid both times even though she was treated for this problem,she is 16 had foals before last one was 3 years ago,so could it also be down to the possibility of natural selection.

We are also unsure as of what to do with her next year as we all know when things don't go the way we hoped it all starts to get very expensive,not that you should go into these things blinkered.

Very interesting post.

 

[AndyPandy]

Apart from the above AP. do you think the weather could also have played a part? We were lucky enough to get our 5 mares in foal this season, but I know other studs were not so lucky and blamed the weather.

I also know of studs who blame the weather... others who blame various things or say (as some say every year) "this has been a particularly bad year".

I honestly don't believe that the weather (especially the non-extremes that we're talking about here) plays that much of a role (if any) in a mare's fertility. If someone can point me in the direction of peer-reviewed research (not anecdotal evidence though) that suggests anything to the contrary; please let me know.

 

[AndyPandy]

I was thinking along the same lines as Honey08 as our mare was similar this year.

AI'd twice but she did retain fluid both times even though she was treated for this problem,she is 16 had foals before last one was 3 years ago,so could it also be down to the possibility of natural selection.

How was she treated for the fluid? 9 times out of 10, not enough is done! 4-6 hourly injections of oxytocin for at least 3 days after breeding (assuming proximity to ovulation), lunge work and/or repeated aggressive teasing by a stallion (amongst other treatments) may be necessary for a mare with delayed uterine clearance issues.

I would pretty much guarantee that if everything else was done correctly, then the level of treatment was inadequate and that then becomes a likely reason why your mare is not pregnant...

 

[Flyingbuck]

I also know of studs who blame the weather... others who blame various things or say (as some say every year) "this has been a particularly bad year".

I honestly don't believe that the weather (especially the non-extremes that we're talking about here) plays that much of a role (if any) in a mare's fertility. If someone can point me in the direction of peer-reviewed research (not anecdotal evidence though) that suggests anything to the contrary; please let me know.

Thanks for your reply, AP - I suspected as much, but nice to have it confirmed.

 

[AndyPandy]

Thanks for your reply, AP - I suspected as much, but nice to have it confirmed.

Not confirmed at all; just my opinion

 

[Flyingbuck]

Not confirmed at all; just my opinion

Yes, point taken

 

[ruby1]

She was treated with reprocine and cleaned out with saline but not anywhere near as much as you have suggested.She was a bit over weight also which may not have helped,thanks.

 

[Honey08]

Need more info:

Your mare's age
Your mare's status (maiden, foaling, barren, empty)
Stallion's age
Covering method (single natural, repeated natural, fresh AI etc)
Stallion's fertility (preferably a first cycle pregnancy rate, rather than "good/great/ok"
The stud's competence (good reputation?)
The vet's competence (well known?)

I bet we can find a problem there before going down the road of stallion-mare incompatibility

Hi, Thanks for the reply, sorry for my slow one - was offline.

My mare is 12, and maiden.
The stallion is about 18. Not sure of his fertility rate. The head girl said it had taken a couple of times with one other mare, but couldn't give you figures. Very well known stallion that has been standing for years there and is their top stallion (I know thats not scientific enough!)
Covered by AI (fresh).
Stud has AI "lab" onsite with vets on site three days a week, and is the training centre for AI for Myerscough college, so seems very competent. The mare was scanned to see where her season was each month. Initially they used regumate to get her to cycle (March) after two injections failed. Following months they injected her in without problems. She was covered four times. Once the follicle (?) didn't grow big enough, but for the other times there was no problem.. Their vets said there was no physical reason, and she didn't retain fluid.

They've suggested getting her flushed out by my vet at home, then stitching her over the winter, putting her on regumate for ten days in March, and sending her on day four to stud. If I do this, which I'm not sure about, I think I'd send her to another of their stallions, which is aged ten.
Thanks, Honey08.

 

[Doncella]

I sent my mare to Merit a TB now standing in Wales. She had previously had a foal by him in 2003. I liked what I got and as the stallion had moved to within 50 miles we tried again in 2009. In 2008 I had sent her to another stud and no luck, thinking she was too old at 18 I tried with Merit when he first moved down here no luck again.
However......
Stud owner changed her covering policy, as they were an ex beef cattle yard she turned the crew yards into individual pens, Merit in the middle and his women round the edges. Rather than use a teaser the stallion chose who wanted to cover and the mares chose when to be covered. Stud owner just opened the gate, let them get on with it and bingo.
My mare at 20 is in foal first covering to the man of her dreams.
Result! lets pray now for a healthy mare and foal come the spring.

 

[ruby1]

just realised you ment the natural attraction if the mare was actually given the choice to choose. We were also advised that it could be an idea to find a stallion for her to run with to see if mother nature would kick in.

 

[Honey08]

just realised you ment the natural attraction if the mare was actually given the choice to choose. We were also advised that it could be an idea to find a stallion for her to run with to see if mother nature would kick in.

Someone said that to me too. Said some horses don't take with AI.

 

[Heidiham]

There are so many possibilities for non conception. Thankfully we can do a lot for many of them. Every mare and every stallion is an individual however and it's important not to forget this. Mare/stallion incompatibility is well down our list of possiblities but can happen and stallions can certainly have a type. Why not? - don't we all?! We knew a stallion for natural covering who was only really interested in grey mares...................... but then his mother was grey.........

 

[Honey08]

Hi, Thanks for the reply, sorry for my slow one - was offline.

My mare is 12, and maiden.
The stallion is about 18. Not sure of his fertility rate. The head girl said it had taken a couple of times with one other mare, but couldn't give you figures. Very well known stallion that has been standing for years there and is their top stallion (I know thats not scientific enough!)
Covered by AI (fresh).
Stud has AI "lab" onsite with vets on site three days a week, and is the training centre for AI for Myerscough college, so seems very competent. The mare was scanned to see where her season was each month. Initially they used regumate to get her to cycle (March) after two injections failed. Following months they injected her in without problems. She was covered four times. Once the follicle (?) didn't grow big enough, but for the other times there was no problem.. Their vets said there was no physical reason, and she didn't retain fluid.

They've suggested getting her flushed out by my vet at home, then stitching her over the winter, putting her on regumate for ten days in March, and sending her on day four to stud. If I do this, which I'm not sure about, I think I'd send her to another of their stallions, which is aged ten.
Thanks, Honey08.

Bumping this up as would be interested in your views Andy..

 

[AndyPandy]

Bumping this up as would be interested in your views Andy..

*12 year old maiden... just on the borderline of becoming an "older maiden" so will probably need more attention than others (info on breeding older maidens here http://www.equine-reproduction.com/articles/MaidenMare.shtml)

*Not enough info on the stallion, I'm afraid! Need to know fertility rates

*4 covers and no pregnancy... alarm bells should be ringing; especially if she "doesn't retain fluid". I would be thinking that she could have picked up an infection on the first or second cycle... has she has a culture and cytology done?

*The Regumate post (I assume) PG injections in March(!) suggest that perhaps not enough scanning is being done, or the scans are being interpreted poorly (this is pure speculation, however). In March, most mares are still transitional (i.e. not cycling and not ovulating) and this is generally clear from scanning!

*What are they expecting flushing and stitching to do? Does she have poor reproductive conformation? Is she a pneumovagina or pneumouterus mare? If so, this should have been dealt with my the stud when she was bred. (Vulval conformation info here http://www.equine-reproduction.com/articles/VulvalConformation.shtml)

*I also don't understand the random sticking her on Regumate and taking her to stud on day 4!? (Info about Regumate here http://www.equine-reproduction.com/articles/Progestin.shtml)

This all seems a bit peculiar to me. If I were a mare owner it would certainly be ringing alarm bells! Please note that this is just my interpretation and without seeing the full history, scans etc. it is difficult to comment accurately!

 

[Touchwood]

I would echo AP's reply above.

I really dislike using Regumate unless absolutely necessary. In this country, a mare not cycling in March is no cause for alarm.....this year most of them had only just had the snow thaw out by then!! What they need is the sun on the backs and the spring grass in their bellies. If come late April/May there is STILL nothing going on, then yes - maybe it needs looking at. The vast majority of mares though will respond to a Prostoglandin injection, and there is no need for Regumate which can really mess them up.

 

[Touchwood]

Apart from the above AP. do you think the weather could also have played a part? We were lucky enough to get our 5 mares in foal this season, but I know other studs were not so lucky and blamed the weather.

FB, I also hear a lot of people blaming the weather......in our experience, it plays a part in STARTING mares cycling in the spring, and ENDING them cycling in the Autumn. However, if a mare is not cycling properly there is little point in inseminating them, so it shouldn't affect pregnancy rates Once the mare is cycling (be that nature or drug induced), I have found the weather has no impact.

 

[Flyingbuck]

FB, I also hear a lot of people blaming the weather......in our experience, it plays a part in STARTING mares cycling in the spring, and ENDING them cycling in the Autumn. However, if a mare is not cycling properly there is little point in inseminating them, so it shouldn't affect pregnancy rates Once the mare is cycling (be that nature or drug induced), I have found the weather has no impact.

Thank you.

 

[Honey08]

*12 year old maiden... just on the borderline of becoming an "older maiden" so will probably need more attention than others (info on breeding older maidens here http://www.equine-reproduction.com/articles/MaidenMare.shtml)

*Not enough info on the stallion, I'm afraid! Need to know fertility rates

*4 covers and no pregnancy... alarm bells should be ringing; especially if she "doesn't retain fluid". I would be thinking that she could have picked up an infection on the first or second cycle... has she has a culture and cytology done?

*The Regumate post (I assume) PG injections in March(!) suggest that perhaps not enough scanning is being done, or the scans are being interpreted poorly (this is pure speculation, however). In March, most mares are still transitional (i.e. not cycling and not ovulating) and this is generally clear from scanning!

*What are they expecting flushing and stitching to do? Does she have poor reproductive conformation? Is she a pneumovagina or pneumouterus mare? If so, this should have been dealt with my the stud when she was bred. (Vulval conformation info here http://www.equine-reproduction.com/articles/VulvalConformation.shtml)

*I also don't understand the random sticking her on Regumate and taking her to stud on day 4!? (Info about Regumate here http://www.equine-reproduction.com/articles/Progestin.shtml)

This all seems a bit peculiar to me. If I were a mare owner it would certainly be ringing alarm bells! Please note that this is just my interpretation and without seeing the full history, scans etc. it is difficult to comment accurately!

Thanks very much for your comments. Very kind of you. Same goes to everyone else.

Her reproductive conformation looks ok to me, however breeding is not my area.. When I had her vetted, they mentioned that if I ever bred from her she may need caslick.. I mentioned this to my own vet before she went to stud, and he thought that she was fine, as did the stud.

Before she went to stud, when my vet performed the swabs, they came back as showing very slight levels of streptococus (could be spelt wrong..) She was given antibiotics before going to stud to clear this.

They tried injecting her into season twice before using regumate. She had been there about a month before this (went mid March, regumate mid April..)

I think their idea of flushing and then stitching was to sterilise the area, and "let everything settle" before trying again next Spring.. Yes this did seem strange. Re using regumate before sending her again, they said it was to "throw everything at one more try.."

I have had my doubts about the stud, the owner is quite hard to talk to, but her staff are great. It is a well known stud, and I know a couple of other people who have used it with no problems, one of whom used the same stallion (but four years ago). The person I know that sent her mare last year, said it was in foal within six weeks. I'm nervous about how to go about questioning the stud too..

My friend that had a foal by the stallion that I was interested in has kept it entire, and said that I could turn my mare out to run with him this summer, to see if nature works better. I have to admit that this is more tempting than sending her back to stud, but I do have a free return option, and have spent nearly a thousand so far! I'm also tempted to give up and go back to eventing her, as she was a good competition horse, and I don't feel like wasting another season while she is getting older... Decisions decisions!

 

[angrovestud]

have you considered that the change away from home might be the problem, we see quiet a large number of mares here but this year we had 4 mares that did not show there season to our stallion and he was in the field ext to them! after three weeks and nothing we elected to use regumate and they all cam in to season when injected on and they were all but 1 scanned in foal I may also add that one of these mares was owned by 2 vets!
I do think that mares can just decide not to! sounds odd but our experience of having our boy out there with them not running together as that would not be practical but we also had a mare that was a maiden that refused to show in season vet advised regumate and then injected on a big fat 0 nothing she was sold three weeks later she was AI and was in season but silent so there seems to be a lot going on the dineamics of the herd for a strt lead mare here has to be covered first then the rest if lead is not pregnant dont expect others to be, we have also noticed and so has our vet for 5 years now that if visitos in field with mare that does not hold to cover and she is lead mare other mares dont hold.
find your lead mare get her pregnant and everybody follows we have learnt from covering over 20 mares per year with 1 stallion

 

[AndyPandy]

Angrove - a useful article about the phenomenon you are describing can be found here:
http://www.equine-reproduction.com/articles/silent.htm

Silent heat is one of the reasons why ultrasonography is so vital in a successful breeding programme

 

[Touchwood]

We use teasing alongside scanning here, it is useful for some mares; and mares not showing in season are incredibly common. For any number of reasons - she is young and nervous, foal at foot, just not very bothered!! It does NOT mean she is not cycling and it is so important to scan too.

If I had a pound for every mare owner who dropped their mare off and said they didn't think she had ever been in season I would be rich!

 

[linali]

I would love to hear peoples views on mares that will not get pregnant when they have a foal at foot, I should add that I mean with no obvious reasons why not ie no pooling, good semen ect